Bron-Yr-Aur from led zepplin I think its 2.37 of twelve string guitar genius by Jimmy Page I was into heavy metal (by that i mean black sabbath led zepp ac/dc iron maiden)

This is very good and if he is a real fan of decent heavy metal (not thrash rock speed metal death metal or HM overkill and over medern varients) he should already know some of the classic heavy metal ballad stuff featuring acoustic guiar Page is hard to best and if you are looking for cross over here is a good place to start.

off topic I once played Battle of Evermore from Led zep 4 (featuring page on mandolin and sandy denny on vocals with plant) to leadfingers and he said "the chord structure was a bit repetitive" well the man used to be into Jazz, what can i say 8-)

Cllr