I think olive drab is probably a little too dark. The original material is Zinc Chromate paint, an anticorrosion compound. Read up on it here. It's still available.
I would certainly never disagree with your impressive knowledge on this or any other subject pertaining to Chrysler Corp. built vehicles, but in my opinion, Zinc Chromate has more of a yellow tinge to it than what you see on the nos clips in the above pictures. Maybe it ages to an olive drab color after 40 years. my 1966 Coronet 500 conv that I restored years ago had what seemed like a million of those clips holding on all the trim. I guess in my old age I remember them being darker in color...