CatBus said:

EDIT: This does bring up a film purity question, though. If the films from this era were all projected with a heavily biased light source, which is the accurate color? Is the film in the can or the film on the screen definitive? I think a fairly strong case could be made that WOWOW may represent the colors of the film "in the can", which nobody actually saw until much later, while the Blu-ray represents the colors of the film "on the screen" which only looked that way due to the very yellow bulbs in common use at the time. IMO neither colors would be "wrong" or "not original", although only the yellowish ones could be fairly called "theatrical".

This is quite easy actually, the original colors are those the director and the DP would have seen when viewing the dailies and doing the color-timing and since they would have used the same warm bulb, which was the standard back then, it is quite clear they would have seen the warmer colors.

From a slightly philosophical point of view, there are no fixed colors on a film print - the colors will always depend on what kind of light you'll shine through the film, just like real-life colors are different depending on the lighting conditions and possibly also the beholder.

So the only thing you can use as a guide as to what the colors on the film "actually are" is what was the standard color of the light that was being shined through it when the people responsible for deciding the look of the film were viewing it at the time.