Riveted dealer nameplates were common in the Southeast US in the 60s. My 68 --originally from Florida-- has five small holes and I hunted for a nameplate. Finally spoke with the General Manager of the dealership and he said, "We haven't had those for 30 years! Wish I had some though. Now they are a collector's item!"
I also remember my father telling my great uncle who managed the Chevy dealership in my hometown, when we bought the 61 Impala that I eventually drove in high school, "Don't let anyone punch holes in it!" When I bought my first car as an adult in 72, my great uncle remembered and did not glue one of those plastic plates on it.
Next time I have it painted, I'm just going to plug the holes. It's not actually the way it came from the factory, anyway.
Good luck in your search!