340 build

Id like to calculate compression as it sits now so that if need be I can have any machine work done to get to my ideal compression ratio but Ive never checked deck height on an engine where the piston sat above the deck surface already?????

When I set the used fel-pro head gasket on there it is just barely below the top of the head gasket.

How so I measure this?

I see reading past posts that a 340 of this vintage would typically have its pistons sitting above the deck surface, so again how do I do the math.

The engine came to me with Edelbrock Performer aluminum heads which I am planning to use as well.

It has also been bored .060 over and has speed-pro pistons in it which I still have the box for

I could be wrong but it looks like there was light contact at one point between the intake valves and the tops of the pistons. Very light mushing in some spots of the pistons.