I bought a product called fusion made by Krylon. It is made for plastic lawn furniture. I did the whole inside of my 70 Cuda using black. They have glossy black, satin, and flat. I clean the parts with dawn prepsol and then with Dawn a couple of times. let them dry and put coats on all of the pieces. When I was done I hit it with clear coat.

It has been three years and everything is still good. Every once in a while one of the surfaces will get marred. When it does it put a quick hit of clear coat and all is good.