I've built several race engines with painted internals, and the only way we found to keep it from peeling was to smooth the entire inside of the crankcase or the valve valley with a die grinder before applying the paint. The rough-cast surfaces simply couldn't be cleaned well enough to make the paint stick. We tried Rust-Oleum high-temperature engine paint and Glyptal transformer paint, and the Glyptal worked a lot better.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!