I have been around Camaros for a while and can say that I learn something new about them all the time.
I have inspected more than a few original paint Camaros and what I can say it that I personally have never seen an original paint first generation tail panel which was painted Flat Black or Satin Black, while I have seen original paint first gens, painted with Gloss Black lacquer. Not saying that it won't happen but thus far never has. The fact regarding the degree of gloss is subjective and can be visually affected by several factors, including the base color of the actual car.
Some of the original cars had very little Black paint on them, maybe two coats and you could even see the base color poking through in some areas. This provided for a less shiny black in some cases but it was still Gloss Black lacquer.
Once again these have been unfattened Gloss Black Lacquer. Wether or not is was buffed to a mirror finish afterwards, (which I do not believe it was) doesn't change that they were Gloss Black Lacquer paint.
While wet sanded, buffed and polished Gloss Black will look different than non detailed Gloss Black lacquer, it is still gloss black lacquer and not the same as "satin" or "flat"
Chevelles, Mopars ect may or may not follow this patern and should not be used as a reference as to what may or may not have been done with Camaros.