Steve
there are two critical things when it comes to refreshing a cylinder head surface ….. how clean they are, and how uniformly flat they are.
Those heads certainly appear to be clean, but have you done any checks for flatness?
A machine shop test would be best, but a good straight edge, and some back lighting could give a good seat-of-the-pants evaluation.
Is it possible to do some sort of a test like is done on body work, using two colors of primer to find high and low spots? Metal bluing solution and crocus cloth?
🤷♂️🤷♂️
Larry