What a 383 does NOT share in common with the HEMI.... does it really even bear mentioning?
Go watch Nick's garage. He has notoriously conservative Dyno. He built a numbers matching hemi, right down to the points ignition. That bad boy made damn close to 500 HP, bone stock, manifolds and all!
The factory 383 would struggle to get to 400. It's just not the same league.
Correlating different engines based on bore sizes (and other such metrics like rod ratio, bore and stroke ratio etc) is misinforming people. That's the little **** that barely matters.