Well, one of the exhaust manifold paints should survive the temperature, can't really see it surviving the lead, though. Ceramic sprays are a possibility, but expensive, and what'll the lead do?
Surely, traditionally they're not painted?
I think -- if I wanted such a thing -- I might make them out of stainless or even titanium (if the titanium fairy still wants to leave some more in my backyard), even then, I'd worry a bit about what the lead would do to them.