Joel said:

I don't mean to belabor the point, but it would seem, theoretically, that a 70mm print would be able to preserve more detail than a 35mm print from the same interpositive. Is this not the case?

Possibly, but they are cropped, and they are very likely to be faded. So you may get more detail, but less picture area and much worse color.

The most useful things that could be gained from a 70mm would be the soundtracks, and the original, slightly different earlier version of Empire.