I am in the process of rebuilding the engine in my 1968 AMX, the engine is a 390, I would like to know if anybody would happen to know what part number the engine paint would be, either in Plasticote or another paint manufacture.
Any help would be appreciated.

I had an AMX in the shop and we simply bought the paint from Kennedy listed in AMX parts /google. We then sprayed it out and had our paint store match it so we could use spray gun to lay it out nice. Your auto paint store may have a code for amc engines.