I have a 1974 Merc 20 HP and I am wanting to repaint it. What kind of paint should I use? I know to use zinc chromate primer, but I want a good paint that is not going to flake off when I run it. Krylon is not going to cut it, I have tried this, and it does not work. Should I use automotive grade paint, or is there something better? Also can this cast alunimum be welded? I broke the corner off of the cavitation plate, this will be covered by a hydrofoil, but I still want it fixed. Any help is appreciated.