It seems that other than just rumors and eyewitness reports (as well as in in theater recording of the 70 mm version), we now have official word what was changed and someone could use this to make a 70 mm cut of TESB.
https://www.starwars.com/news/empire-at-40-star-wars-the-empire-strikes-back-ending-changes?
Good to see some detail on this at last… Gary Kurtz has mentioned it a few times in interviews in the early 2000’s (IIRC… Lucas’ ‘good enough’ attitude sneaking in for a 1/2 sub-standard shots for this last-minute scene towards the end of Empire - yet Kurtz wanting to ‘get it right’).