"11.5:1 pistons" are only that with the correct deck clearance, chamber volume, and gasket thickness.

Do some measuring/CC-ing so you know what you actually have.

It may or may not really be 11.5:1.

68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads