There is an International Uncut and a U.S. Director’s Cut with differing material: https://www.imdb.com/title/tt0091203/alternateversions?tab=cz&ref_=tt_trv_alt
Most edits I’ve seen are of Highlander II, but there is at least one recent edit of the first film: https://ifdb.fanedit.org/highlander-the-black-knight/
There are flashback scenes in Highlander II. There might be some useful material there that could be brought into the first film.