OK, poita confirmed to me in email that the scan can be tweaked to look closer to the print, but as far as saturation, it can be increased maybe "another 2-3%". He confirms that the print as projected is not very saturated, and that the 35mm stills from eBay are oversaturated "as is often the case with taking photos with digital cameras."
Very intriguing, I wonder why taking photos of a film print would amp up the saturation compared to when the print is actually projected. That means that even theatrical prints contain more color information than would be seen in a theater?
This is is more proof that everything we know is wrong about how movies looked in theatrical release, and that just because a recent video regrade is very different from older video transfers, doesn't make the older transfers any more accurate. It also lends credence to my theory that many of these "revisionist" regrades can in some ways be closer to the theatrical timing, while still being botched and marred by revisionist tendencies (teal skies, Jersey Shore spray-tan complexions, contrast being both crushed and flattened, etc.)
This is why I'm so glad to see amateur 35mm scanning of original release prints becoming a reality.