Engine painting

If you have it completly degreased, I would buy a gallon of laquar thinner or Acetone.
Using clean rags wipe with a wet rag with solvent followed by dry rag.
You will be suprised how much more cleaning you will have to do to the motor.

I don't think I would use POR 15 on a motor, it is supposed to be used over rusty metal.
Go to your local NAPA and pick up two cans of engine enamel jpaint and you should be good.