Help with Head Gasket selection

What you are calling quench is also your piston to head clearance. You need to measure your pistons again to see precisely how much out of the hole every piston is. You used your shortest measurement to get .030 piston to head clearance, but your higher .027 only gives you .028 piston to head clearance. i would not risk running it that close on a nice standard bore 340.
if the stock pistons are staying in place and highest one is .027 out of the hole, and I was doing this, I would mill the heads to get 58 cc chambers, then run a .065 thick Cometic gasket with 4.06 specified bore. That brings you back to a 10.43 to 1 compression without running the piston to head clearance really tight. Need to check piston to valve clearance before milling the heads though, too. But that is my novice guess.