The ‘4️⃣ • The various Releases / Editions / Sets / Versions (the changes to them)…’ of ❕ An Index & Help Thread for Theatrical Cuts vs. Subsequent Releases ❕ has a few discussion threads on the 70mm for Empire Strikes Back (and Star Wars too).
I think this thread may also be of interest (among others): Empire Strikes Back - Two 1980 Theatrical Cuts? (re 70mm)
TSWT forums also have a project thread (or two) underway for the 70mm of Empire Strikes Back.