[Maédhros]

Now this is an interesting issue. There are really two distinct things for us to think about here:

1. The Narn - is the projected revision that extends the history of the Dragon-helm beyond the battle on Amon Rudh workable or not? It would require some revision to the Narn, and it's hard to judge how much. If it's not, then the Dragon-helm was not in Brethil, and of course cannot be mentioned here.

2. The Wanderings of Hurin - the note suggesting that Hurin was given the Dragon-helm comes from before the development of the "Hurin in Brethil" story, and indeed from before the development of the character of Hardang. The note has the new lord of the people give the helm to Hurin - but Hardang does not do this in "Wanderings" (and indeed it is very difficult to imagine him doing so). The early conception seems to have been that the new lord would have been friendly with Hurin. For Hurin to receive the Dragon-helm now would require a different story.

Even if we could justify it, it is no easy matter to insert it into the text. It is very awkward to simply say "he was given the Dragon-helm".

For these reasons I fear it may prove impossible for us to use the Dragon-helm (though I admit I would very much like to if it were possible).

I really don't think that it is an impossibility at all consider the following:
From the Narn

When all in the camp were sleeping Beleg took his bow, and in the darkness shot the wolf-sentinels, one by one and silently. Then in great peril they entered in, and they found Túrin fettered hand and foot and tied to a withered tree; and all about him knives that had been cast at him were embedded in the trunk, and he was senseless in a sleep of great weariness. But Beleg and Gwindor cut the bonds that held him, and lifting him they carried him out of the dell; yet they could bear him no further than to a thicket of thorn-trees a little way above. There they laid him down; and now the storm drew very near. Beleg drew his sword Anglachel, and with it he cut the fetters that bound Túrin; but fate was that day more strong, for the blade slipped as he cut the shackles, and Túrin's foot was pricked. Then he was aroused into a sudden wakefulness of rage and fear, and seeing one bending over him with naked blade he leapt up with a great cry, believing that Orcs were come again to torment him; and grappling with him in the darkness he seized Anglachel, and slew Beleg Cúthalion thinking him a foe.
But as he stood, finding himself free, and ready to sell his life dearly against imagined foes, there came a great flash of lightning above them; and in its light he looked down on Beleg's face. Then Túrin stood stone-still and silent, staring on that dreadful death, knowing what he had done; and so terrible was his face, lit by the lightning that flickered all about them, that Gwindor cowered down upon the ground and dared not raise his eyes.'
But now in the dell beneath the Orcs were aroused, and all the camp was in a tumult; for they feared the thunder that came out of the west, believing that it was sent against them by the great Enemies beyond the Sea. Then a wind arose, and great rains fell, and torrents swept down from the heights of Taur-nu-Fuin; and though Gwindor cried out to Túrin, warning him of their utmost peril, he made no answer, but sat unmoving and unweeping in the tempest beside the body of Beleg Cúthalion.
When morning came the storm was passed away eastward over Lothlann, and the sun of autumn rose hot and bright; but believing that Túrin would have fled far away from that place and all trace of his flight be washed away, the Orcs departed in haste without longer search, and far off Gwindor saw them marching away over the steaming sands of Anfauglith. Thus it came to pass that they returned to Morgoth empty-handed, and left behind them the son of Húrin, who sat crazed and unwitting on the slopes of Taur-nu-Fuin, bearing a burden heavier than their bonds.

And we have the note from Narn: Appendix

It may be noted here that it was my father's intention to extend the history of the Dragon-helm of Dor-lómin into the period of Túrin's so¬journ in Nargothrond and even beyond; but this was never incorporated into the narratives. In the existing versions the Helm disappears with the end of Dor-Cúarthol, in the destruction of the outlaws' stronghold on Amon Rûdh; but in some way it was to reappear in Túrin's possession at Nargothrond. It could only have come there if it had been taken by the Orcs that carried Túrin off to Angband; but its recovery from them at the time of Túrin's rescue by Beleg and Gwindor would have required some development of the narrative at that point.
An isolated scrap of writing tells that in Nargothrond Túrin would not wear the Helm again "lest it reveal him", but that he wore it when he went to the Battle of Tumhalad (The Silmarillion p.212, where he is said to have worn the Dwarf-mask that he found in the armouries of Nargothrond).

Now, is it possible that the Orcs carried some ransom from Dor-Cúarthol, such as the Dragon-Helm? I think that that is quite possible. Also we have from the narrative of the Narn that the Orcs that captured Túrin left in a hurry and could therefore could have left some of the "booty" that they had taken from the Outlaws.
Should the text be edited so as to mention it explicitly that the Dragon-Helm was retrieved by Túrin at that point, I don't think it is necessary. Consider that the Ring of Barahir, along with the other items survived in Númenor, yet they were not mentioned exaclty how it was so.
From Unfinished Tales: DESCRIPTION OF THE ISLAND OF NÚMENOR

The King's sword was indeed Aranrúth, the sword of Elu Thingol of Doriath in Beleriand, that had descended to Elros from Elwing his mother. Other heirlooms there were beside: the Ring of Barahir; the great Axe of Tuor, father of Eärendil; and the Bow of Bregor of the House of Bëor. Only the Ring of Barahir father of Beren One-hand survived the Downfall; for it was given by Tar-Elendil to his daughter Silmarien and was preserved in the House of the Lords if Andunië, of whom the last was Elendil the Faithful who fled from the wrack of Númenor to Middle-earth. [Author's note.]—The story of the Ring of Barahir is told in The Silmarillion, Chapter XIX, and its later history in The Lord of the Rings Appendix A (I, iii and v). Of "the great Axe of Tuor" there is no mention in The Silmarillion, but it is named and described in the original "Fall of Gondolin" (1916-17, see p. iv), where it is said that in Gondolin Tuor carried an axe rather than a sword, and that he named it in the speech of the peo¬ple of Gondolin Dramborleg. In a list of names accompanying the tale Dramborleg is translated "Thudder-Sharp": "the axe of Tuor that smote both a heavy dint as of a club and cleft as a sword."

If such items such as the Aranrúth had survived, consider that in our Revised Silmarillion we do not even make a mention of it, and if there is a possibility that the Helm could be regained by Túrin after the departure from the Orcs, I think that it is possible for use to at least try and retain other aspects from the Appendix of the Narn such as:

For fear of that helm all foes avoided him, and thus it was that he came off unhurt from that deadly field. It was thus that he came back to Nargothrond wearing the Dragon-helm, and Glaurung, de¬siring to rid Túrin of its aid and protection (since he himself feared it), taunted him, saying that surely Túrin claimed to be his vassal and retainer, since he bore his master's likeness on the crest of his helm.
But Túrin answered: "Thou liest, and knowest it. For this image was made in scorn of thee; and while there one to bear it doubt shall ever assail thee, lest the bearer deal thee thy doom."
"Then it must await a master of another name," said Glaurung; "for Túrin son of Húrin I do not fear. Otherwise is it. For he has not the hardihood to look me in the face, openly."
And indeed so great was the terror of the Dragon that Túrin dared not look straight upon his eye, but had kept the visor of his helmet down, shielding his face, and in his parley had looked no higher than Glaurung's feet. But being thus taunted, in pride and rashness he thrust up the visor and looked Glaurung in the eye.

I think that we should at least make an effort to retain those parts from the Appendix in our Túrin Chapter.