I would use a non-catalyzed primer, and don't soak it. However, as pointed out; It has to be absolutely clean. Don't use something like POR. It won't come off and it doesn't deal well with UV or heat long term. I have used "bomb can" ceramic Corporate blue with the same gloss clear coat. It actually seems to hold up rather well if the engine is tuned well, even on a big block, where the exhaust exits.