383 or 440 Dilema
The performance 383 was not a powerful engine. At 330 or so HP, it doesn't rate. But that doesn't matter since modifications fix the ill's.
Do a 440 and rest well.
The 440 in OE trim wacks out 375 HP. Add headers, intake and a open air cleaner, yea, your making clearly over 425 and it still has the stock cam and compression.
Add a small cam (just bigger than stock!) and you can add another 25hp and still run cheap pump swill.