360 la

Were those pistons nearly flush with the deck?
My 360 with those pistons was about 10.7:1 pistons were @ zero deck with 65cc heads and a .040 gasket.

Even if they are down in the hole you’ll likely have some pretty decent compression.

Get a compression tester, remove all the plugs, wire the carb so it is wide open. Measure each cylinder by rotating the engine 4-5 times for each cylinder. Let us know what your cranking compression is, I’d bet you are in the 180 -185 range.

my bet is you have high compression and your cam is working against the engine.