The paint suppliers in the Antique Outboarder magazine have excellent reputations although I have never used them. As an amateur , I use spray cans only and have had good results with red Dupli-Color Engine Enamel with ceramic “withstands heat to 500F”. I also use their primer. Can’t remember if it is the self self etching auto primer or if it is unique to the engine enamel. This paint is available at NAPA or Advance Auto. I have not had problems with paint softening. To me the color match with original looks fine. The paint can be scratched and after several seasons of constant use will definitely show wear. That is ok by me as my rig is used a lot. If you search Google with AOMCI paint you can see what the pros use.
OK, found the Dupli-Color paint numbers I have used all are Engine Enamel with ceramic:
Red is DE1653 Red
Primer is DE1612 Gray Primer
Black for the top is DE1613 Gloss Black