What piston have you selected? A lot of 383 stroker pistons come with the .990 (chev) pin diameter instead of the 1.094 (mopar) diameter. You may have to follow what AndyF says above.
My block is 40 over so I have to have a custom piston made which is going to be 10.5 to 1 And I’m looking at a solid camshaft around 550 lift I don’t know what the projected horsepower will be