Are you talking about spray paint? Most people just use regular rattle cans if they are spray painting the frame. I don't think you need to worry about heat, really. The engine mounts are only on the cases and they don't really get HOT when the engine is running. The cylinder is what gets hot.
The good thing about heat resistant paint is that it needs to be cured, and is tough to get off after cured. You could spray your frame with it, and then run a heat gun or even a torch over the paint so it cures. Stuff is surprisingly tough