[A1971Blazer]

I've painted a few smaller parts by blasting with aluminum oxide media, acid etching with aluminum brightener, the immediately priming with either self-etching or epoxy primer.
I think the hardest part of painting an entire aluminum engine would be getting all the oxidation off and getting it clean enough for the paint to stick and stay on over a long period of time.
I debated painting my aluminum LS but ultimately just cleaned it and left it as is,
after all it's not going to rust....