IMO, if you have to pay for new valves and the associated labor to install them, then do some blending, so you actually see some benefit from the bigger valves, then I'd just spend a little more and get new aluminum heads.
A set of Stealths or Sidewinders with a little clean up would come in at around your $1500 budget.

68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads