Painting a motor

[Jeffh]

Have the motor out and getting ready to paint it. Looking for advice. I have thoroughly cleaned it and bead blasted the valve covers and other minor small parts down to bare metal while the bulk of the motor varies between solid Chevy orange and bare cast iron. I am changing colors from the Chevy orange. What kind of primer do I need to use? Just a everyday driver type truck that I would like to look as nice as budget will allow. Being the motor its bound to eventually get oily/dirty anyway. The local parts place in my small town sells Nason products and can mix the topcoat color I want. Temperatures are in the mid 60's where I am too. In the past (its been a few years ago) I used PPG Trio Prime spotted over the bare spots and top coated with Imron and was and still am very happy with it. Anybody have and suggestions?