An obsession I've had since high school is to paint the inside of the engine. Vick Wagner, an old race engine builder in Knoxville taught me that. Click for engine details I use as bright a white as I can find. The white allows me to see metal shavings or other contamination's in the oil. Any paint, however, will seal the pores in the cast iron block that would otherwise trap dirt and metal shavings.
Dirt then flows back to the oil pan where it gets trapped by the oil filter.
After painting the inside, I then use steel-wool to remove those inevitable bits of paint that get in the cam journals and lifter areas. Blow through it with an air hose to get rid of the steel-wool shavings. I paint the outside of the block hi-temperature Chevy blue. Then I stuff goodies into it. It has a gross valve lift of around .487 exhaust, .495 intake, and a lobe separation of 110 degrees.