Epoxy prime everything including the Aluminum and the paint will really stick. Let the epoxy dry 1/2 hour before applying the top coat. Any brand of two part epoxy from an automotive paint store should work. The green/gray has the most zinc for best adhesion.
I never use a spray can paint on my engines. I use either Urethane single stage or Arcylic Enamel with Hardner over the epoxy.
The catalized paint will not be affected by solvents or stain after dry.
For Y-Block red I use early 60's Ford truck "Rangoon Red" formula. It is red with a orange tint and looks like the original, but is more vibrant and lasts better than any spray can stuff.
Using the automotive based paint and primer does add to the price, but it will last and look great.
Pat Fleischman
