[edit] after further reading, it appears the American 1990 widescreen laserdiscs for Empire and Jedi are the exact same transfers as the Japanese Collections, but Star Wars was completely re-done because of the shrinking ratio problem that came when porting the Japanese over to the American in it's first run.
So in theory, the US Empire and Jedi widescreen Laserdiscs, pre-1992, should be the EXACT same transfers as the Japanese Collection ones. According to Davis DVD, that is. Japanese is 3 CAV discs, though, and US was 2 CLV discs