Used the VHT flameproof on my dumpie.
Just sanded surface rust off, gave it a good wipe down with acetone, then sprayed it, didn't bother with primer, cured it in the oven (nearly caused a domestic ). Does the job. Havn't had any problems yet.
LOL I know what you mean, I had fun curing my valve cover, stunk the house out and got the evils from the girlfriend.
They just dont understand the bond we have with our cars do they.
Ive scrubbed the primer and clear off my list as well, seems the clear may go yellow over time, and the primer only helps on smoother surfaces.
Cast manifold is rough as so as you say provided its clean it should stick.