There was an article posted a while back in the King Kong thread (I think), about merging soft colored images with sharp desaturated images. To be more specific, it was about the restoration of an old Doctor Who episode. BBC only had an original copy in black and white of what was originally a color episode. They found somebody that had made a color tape recording of the show, but was obviously much softer than the source B&W copy. So they layered the color image over the black and white, and came up with an image that was better than the two images going into it. Obviously, this would be a major pain in the ass in this case, as there's probably incocnsistencies in frame counts for various scenes, plus the videos would have to be re-encoded to have identical aspect ratios (and resolutions?). Also, there's the trick of actually merging the two. But I think this would be something worth looking into, because while the color is better on the new workprint.
Also, the less saturated (older) workprint you're showing--this isn't the one you just got in the mail, is it?