As I said before, someone did one. I have it lying around ... pre-ANH crawl. Sub-TR47 transfer, but decent. Used clips from it in Deleted Magic. You use the audio button to switch from stereo to mono soundtracks.
Got it from Sluggo ... it's not something that's supposed to be widely passed around though. Hasn't been torrented.
EDIT: Oop! Just noticed this thread ... Looks like you're talking about the same pre-ANH mono edit that Sluggo gave me. Haven't read the whole thread yet.
http://originaltrilogy.com/forum/messageview.cfm?catid=9&threadid=1703&STARTPAGE=6