zero deck pistons?

They way I'd go is take all 8 and check the hieght in the #1 crank throw. Then take the longest and measure at #2, #7, na d#8. You only have to measure along the pin axis as that measurement will be the same as averaging the tall side and the short side. Be prepared if the block was not square decked. decking the block is not the same operation and chances are good that it was only decked you will have some variance.