To my understanding, Welles did some initial post-production work on Macbeth and then entrusted (or abandoned) it to Richard Wilson (so Welles could go off to Italy to star as Cagliostro.) Republic wanted the Wilson cut shortened and some dialogue re-recorded, and ultimately Welles did a final clean-up edit (apparently in Italy) removing over twenty minutes and providing narration (this is similar to the final clean-up edit he did on RKO's version of Journey into Fear.)
Simon Callow claims that this release version has been available in a lovely print since 1985. It has? Where is it, then? I'll buy a copy. All I know of is the 1970s restored full-length version (restored, I'd have to guess, to Richard Wilson's original vision.) I actually enjoy the release version much more than the restoration (though lovely would be the last word I'd use to describe the copy of the release print I've seen.)
Anyway, here is Welles' opening narration for the release version (you'll notice the re-recorded Witches as well.)
http://www.box.net/shared/tuz51ica0u

