Yes, but an IP is not a simple reversal of the negative, it would already have color-timing applied to it, so what is on an IP of a film timed in the early 80s when projected with a neutral bulb would be wrong, because the IP was timed with a warmer bulb in mind, so if the person who did the color-timing wanted something to be white, they would have timed it so that it was white with a warm bulb, so with a colder bulb, it would look blueish.

What I was trying to say was, that you wouldn't get the colors that are on the IP, but only the colors that appear to be on it when you shine a "neutral" light through it.