Promax or Stealth heads???

I would suggest doing a custom camshaft for your 383 and nothing else at this time, or not even the camshaft now. Both of those heads are ok, but if your goal is a 400 based 470ish build in the future, just start spending money in that direction, then go with the Trick Flow 240 heads for a kick *** street/strip engine.
Do it once and be happier. Best bang for the buck.