This sounds like all custom parts, rods, pistons and ring package, what stroke, which rod journal size and rod length are you wanting to use?
Why use the weak, thin main webbing 383 blocks? Why not use a 400 block to start with?
I am assuming the pistons will be custom......
383 block
4.25 stroke x 4.28 bore with a 6.535 rod
I had two 440 stick shift forged crankshafts offset ground to 3.91 stroke with BB Chevy rod journal sizes with B motor mains, one for my 1969 Dart GTS H code 4 speed car and the other for a 400 block I'll build later.
I bought two sets of BB Chevy type 7.100 long forged I beam rods from Speedway for both motors, neither one should make over 550 HP on pump gas, I think
My first 400 pump gas 4.250 stroke stroker motor used a set of CAT 6.800 long BB Chevy H beam rods, Dan, Dram, called those pistons hockey pucks
They where short and light weight