Stoke stroke 383 horsepower
I've been fooling with a 383 for a bit now, and have some suggestions. Do a BUNCH of checking/measuring before buying pistons. 383's are a pain to get compression out of, and don't tell me "they were 10.0 to 1 stock" because they sure weren't. :) I have flat tops with NO valve reliefs, and milled closed chamber heads, and just touch 10.0 to 1, BUT, you run out of room for a big cam, (needed for your HP goals). OK put in a piston with big notches, compression goes in the toilet. I would also skip the 750 cfm. carb. MM did a build off a stock one, and even at 9.2 to 1, with stock heads/cam, a 950 HP made more HP/torque right from the bottom of the dyno pull. I ran a 750 DP on a stock 2bbl. engine, and it ran beautifully.
If I were to try a dedicated 383 build with 500+ HP in mind, I would go to a 300+ cfm cylinder head, and shoot for a piston with 10-10.5 to 1, up to 11.0 if you use aluminum heads, being you want to stay pump gas. Good rods, stock steel crank is fine. good intake, like the M-1. 850-950 carb. cam in the 250 degree @ .050" range, solid lifter, .575-600" lift. Good valve gear. large tube headers, good ignition. Good luck.