But it'd be a preservation of the IMAX cut of the movie, which, according to the conversation had here, sounds to be somewhat different than the BD cut or the full frame presentation anyway

Any version which would be different from BR would be either non-anamorphic in 4:3 or with black bars on both sides in IMAX scenes. It also won't have all of the IMAX shots which are present on BR cause some of them are not present on DVD.

If you REALLY want something like this, it looks like you will have to do it by yourself :P