There is a link to an article somewhere on this forum that indicates that Lucas and Kurtz received British Dye-Transfer prints (at least of Ep IV). I have never seen a dye-transfer print of Star Wars, but I have seen a couple of other movies and let me tell you, they blow away the regular prints for color reproduction. One of the best things about these prints is that they do not deteriorate in the same way as regular prints, but retain their truer colors for longer. There's no way these prints would have been used for the SE process in '97 (though the original negatives could have been), so they are probably the best source in existence. Getting one on the other hand...

As far as LD tape masters are concerned, that's an interesting idea, but:
1) what tape format were they telecined onto, and is it:
a) higher-res (extremely unlikely) than the LD?
b) significantly less soft/noisy (possibly) than LD?
c) less deterioration prone (possibly) than LD?
2) the tape masters would almopst certainly have been retained by LFL after the pressings.
I suppose there's always hope that an LD mastering employee would have run off an extra master for personal use...