Don’t paint where the gaskets sit. Then when you pull the gaskets it won’t pick up the paint. I usually use the gaskets as a template to tape off a short block for paint.
All aluminum parts should have a light coat of self etch primer. The iron block scuff all machined surfaces to be painted with a coarse scuff pad. Wash all iron surfaces with thinner but avoid self etched primed parts. Then prime the whole thing with engine primer right over the self etch primed parts. Then Paint it what ever color you want withing 1/2 hr.
The above tips are great for Prep. I have had excellent results with Eastwood's 2 part engine paint. Being catalyzed, the paint hardens. I painted the engine in my Cuda 8 years ago, and it still looks good. Plus, it is reasonably priced.