Apologies for going very slightly off-topic but Belbucus did a comparison 70mm in theatre recording in one channel vs the 93 THX audio in the other GOUT synced audio mix posted many years ago in a.b.sw. I believe this particular 70mm recording was used for that comparison mix.
Forget that. Got it wrong.......
http://originaltrilogy.com/forum/topic.cfm/Star-Wars-1977-70mm-sound-mix-recreation-stereo-and-51-versions-now-available/post/549479/#TopicPost549479