I should clarify that an 18cc D-cup piston, like the KB 135 should get you around 9.7:1cr with a 64cc chambered Vortec head on a 383 with 3.75" stroke and 5.7" rods. Though Speedomotive will steer you in the right direction, you should learn about "squish" and how block deck height and head gasket thickness effect final static compression ratio.