Hi,
I've had one 65 that is green, and 2 66's that were red. The 65 looked untouched, the 2 66's I got from evil-bay so not sure they may have been paint from the factory, wouldn't think they would change how they painted engines between model years.
I have heard stories about dealers having stacks of bellhousings in the service departments for people converting cars back then, guessing they would have been raw cast iron
Regards,