compression ratio on pump gas

I was the one who originally recommended the 1st option with higher compression/flat-top pistons. Like my sig says I have a 10.5:1 360 with iron Magnum heads and the smallest Lunati Voodoo cam, and it runs great on mid-grade pump gas. I built this engine all by myself, and it was the first engine I built from the "block-up". If you take your time and buy a couple special tools (dial indicator is the main one) you can build an engine like this with not too much trouble.

My block had been previously decked and was already at spec for zero deck. I used OOTB KB-107 pistons and untouched factory iron 5.9L replacement Magnum heads with stock rocker gear, also stock crank and rods. I cc'd the heads and made sure the chambers matched, then used a Dremel grinder to round off the edges in the chambers and valve reliefs on the piston faces. I used off-the-shelf Mr. Gasket .039" head gaskets and when all was said and done I ended up with about .043" quench checked with both a dial indicator and modeling clay+depth calipers.

I'm at 5500 ft. above sea level and the timing is set to 15 initial, 34 final all in by ~2500 RPM and it runs with no pinging on 87-octane (mid-grade here). Might sound too good to be true for some, but I should have a few videos up here soon to show how responsive and smooth it is (not to mention decent on gas considering the power).

EDIT: I believe the OP is running RHS (or similar) heads which are definitely closed-chamber...