I have found first hand info on what prints were used for the CBS/FOX telecines. 1982 transfer of Star Wars was a release print. The initial releases of TESB and ROTJ were interpositives as was the concurrent release of Star Wars. The 1985 release of the trilogy was also interpositives. Tapes were sent to Lucasfilm, but no one from Lucasfilm was present. And it seems that virtually all films telecined at the CBS/FOX facility were either interpositives or internegatives. One exception was a collection of Chaplin films.

Not a single special telecine print. Not a single 16mm print. And done on a Rank Cinetel 2.

The interview with Wayne Cook can be found here - https://www.youtube.com/watch?v=2LagwssLxlk