Check https://www.youtube.com/watch?v=s1PCI1L709U for a beautiful and spine tingling performance by the Lemster Mannenkoor choir. I can't hear much in the tune apart from the already mentioned Oft In The Stilly Night.
However, since Moore was in the habit of refashioning melodies which he lifted from Edward Bunting's Ancient Music of Ireland, it could be that the tune of See Do Wide See is nearer to Bunting's "original" than to Moore's remake. Can anyone check.
BTW., does anyone have an English translation of the words?