I built a Mopar Mega iron block 572 C.I. pump gas hemi motor several years ago, it has EFI with dual 4150 1150 CFM dry throttle bodies, it had right at 10.8 to 1 true compression ratio and made 799 HP on Oregon 92 octane non ethanol pump swill on a DTS engine dyno in Chico, CA with a set of CNC ported Stage V heads form Tim at FHO
It's going into a 1971 Challenger with a 727 with 3,23 gear with 29 inch tall rear tires, no O.D. or lock up torque converter
I'm going to help my customer get it running, it is a complete ground up build from front to rear. The car was strip completely by a thief several years ago while stored at a friends of his house
Hemiroid motors are a pain in the butt to get the exact true compression ratio, I use a 100 CC burrette to measure the volume in the cylinders with the piston dome down enough to have from .010 to .050 clearance above the dome to the block deck and then calculate the true down volume off of the specs for that motor
Good luck on your build