If we consider a hypothetical official release of the original theatrical versions of the Star Wars Trilogy on Blu Ray, what do you think should/should not be "permitted" in a faithful reconstruction/restoration?
In the case of Star Wars its pretty clear that George Lucas suffered minimal studio interference in the story he was trying to tell. It is true that he had many difficulties involving studio politics and financial restraints but I see little evidence that this ever greatly compromised his story, characterization and overall creative "vision". Did it make the shoot difficult? Definitely. Did he have to spend a lot of time in the editing bay getting the film to work? Absolutely. It took a team of three crack shot editors to mould the film into something coherent in time for the release date, but the results (8 oscar nominations including best picture to say nothing of the box office reception) speak for themselves. This builds a very strong case against the need for *any* changes to the actual final cut of the film. I would certainly extend this conclusion to the rest of the trilogy as well.
What about cosmetic changes?
Apart from the expected removal of film damage and artifacts that have nothing to do with any artistic choice, what else cosmetically should be permitted for the film to still be classed as a "original" release version? I would definitely say that effects re-compositing is allowed in extreme circumstances with the obvious proviso that the original elements still exist and are usable. There's nothing wrong to my mind with minimizing the uglier side-effects of photochemical effects work (especially those done under immense time and financial pressures as the effects shoot on the first film definitely did) so I'd day, if a shot looks dodgy and can be recomposited, go for it. I'd extend this to the cleaning up (but not complete removal) of matte lines on shots that don't warrant recomping. And of course opacity correction on elements is a must. I am also in favor of adjusting the grain on optical elements to match more closely the grain of the live action shoot so the change between a shot with an effect in it and one without is minimized and doesn't distract the audience.
On the subject of colour timing, I believe that the wishes of the cinematographer and director be respected and wherever possible should be done according to the original specifications where records of these still exist. Once that is all set properly then I think one can and should, refer to a selection of prints and other resources as a double-check that the color timing settings that have been applied actually make the film resemble an actual archival element. Color that changes from shot to shot in a single scene should be matched and corrected. I believe that consistency does have the edge over source faithfulness when it comes to correcting an old film, especially one laden with multi generation optical effects. Overall faithfulness to the source over the entire running time of the film is more important, I think, than faithfulness from shot to shot where said shots differed wildly from each other even in the original release.
On the audio side I think a 7.1 lossless setup is entirely acceptable in a restoration of a film that never originally had such a track so long as the overall feel and intentions of the audio are respected. The inclusion of a lossless stereo track to approximate the original 35mm release track would also be a worthwhile feature.
So to sum up, in a hypothetical official release of the theatrical versions I would be happy if they:
fixed matte lines
painted out dirt and damage
stabilized and homogenized film grain
color timed the film for overall faithfulness
included both a faithful uncompressed stereo soundtrack as well as a souped up 7.1. option