I don't use the top of the ring lands to determine the piston height in the bore, try using the top center of a piston on each side at TDC and used those numbers on United machine, KB pistons, web site on their compression calculator tab to see how your motors compares compression ratio with Diamond calculations scope
The true mechanical compression will be a tiny bit less using the center of the piston for the deck height compared to the actual swept volume of that cylinder down to the rings at TDC but I don't figure on a pump gas motor that volume is enough to worry about shruggy
Anything under 10.5 to 1 with aluminum heads on pump gas on the stret is good enough for me up twocents

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)