A 383 w/233,241 roller, 10.5 compression, aluminum heads, air gap, well tuned Holley DP, properly set up ignition, open, tuned headers,
will get you around 500/500. All in a streetable package.
IMO, machine work is critical to HP and longevity. Is rotating assembly balanced to less than 2 grams ?, plate decked ?, crank journals polished ? Hi quality cylinder hone ?
All above is for naught if you’re gonna harness this to a 700r and 3:08 gear.
Question: EFI doesn’t work on low vacuum cams ? Someone school me on this !