I talked with Keith @ Keith Craft about this in detail when I ordered my Pond 482" motor from him. He strongly recommended against any painting or coating on aluminum blocks, (I don't see why that same thinking wouldn't apply to heads either?). The increased rate of expansion with aluminum causes pieces of paint to delaminate and "pop" off, sometimes in large sections, hence my bare bottomed FE.
The discussion with Kieth started with asking for a Glyptol (SP?) coating for the Pond's lifter valley..
Dave