I think for the 383 to make more power than the turbo 5.3 it would have to be pretty radical high compression etc. than that would do you no good for adding the turbo later.

 

its gonna have like 10.4 or 10.2:1 which is the reason for only doing 7psi. i don't want to buy new pistons so these will do for now. if later on i want more i can always get 4" pistons and a 6.0 block and do a 402.