mine is a mopar siamese block, 4.5 X 4.25. 7.1 inch 2.2 big end rods, CP pistons, came out at about 10.25 - 10.4:1 depending on the compression calculator i used. solid roller .605/.585 ~ 242@.50, 112 LSA. stage V heads prepped by tim at FHO. stage V intake with 2 650 edelbrocks. did 712 @ 6000. mine is a street car, hasn't seen the track yet, one of these days...