Is overspray on cylinder head ok?

TT5.9mag said
Yea with Glyptal, and that is an enamel based “paint” but it goes on when the engine is clean, and freshly machined. The rattle can paint on oily valve train parts will not stick and likely end up in the pick up screen. Resulting in a thread on FABO titled “where’d my oil pressure go”?

Correct! I apply Glyptal on almost every motor I build. If used correctly, it has its benefits.

I would personally pull OP's motor apart. Details matter. If a builder is willing to skimp on the parts you can see on the outside, just imagine what you can't see on the inside.