I'd never consider any change to a trim tag. I'm picky about original details like that, and don't believe in misrepresentation at all.
I'm happy to have found what an original '70 SS396 Nova that has what looks to be the original drivetrain in it. My main question was sorting out what the paint color change issues and how it is perceived among various crowds.
At this point, if I get the chance to have the body freshened up someday, I most probably will stick with the Black Cherry color that it is now. One reason - besides the obvious of liking the color - is that what would I do with this fine 1/18 scale Ertl Nova detailed to look like my car if I had the color changed?
http://www.amhost.com/scooter/allensnovapage1.html