A long time ago I made up a rule. And that rule is if a head or a block comes into the shop and the customer says pressure test and check the surface or something similar I never ever bother checking the head or block for flat.
A feeler gauge and straight edge are very crude measurement tools.
So the rule is I don’t bother checking the **** to see if it’s flat. It’s not. They never are. So they get pressure tested or mag’d and then surfaced.
You’d be surprised what a feeler gauge will miss.
It isn’t cost effective to waste time with measurements. Sometimes you can skate by without decking the block but never the heads.
I’d pull it down and deck the block and start over.