Just a couple items here.
I just painted the bright aluminum window moldings on my 82 black.
I used Krylon gloss black, because its cheap, and it will look like new flat black longer than starting with flat black, from past experience.
The one new thing I tried was some stuff called Adhesion Promoter, a clear spray primer, that I found in Advance Auto. Two coats, let it dry 3 minutes and paint. Seemed to make painting the metal and plastic, like the cowl vent and sail panels go easier.
Might be worth a try.
The last owner painted all the moldings on my 89 dark blue body color, which I wish he had not, since it is peeling.....so I am going to have to address that soon.