To Russ's point, I don't know if correct height 1968/69 hp 383 pistons were ever available.
I've never taken apart an original 68/69 hp 383....... Did those motors actually have positive deck height pistons as delivered from the factory?

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