ProCharger or Turbo is the ticket.
We built a 355, Fast XFI and 91.5MM Turbo and the car was making
940+ at the rear wheel.
This was a budget build witha a stock block even.
If you have some funds I would redo it in a Std deck 4.155 bore x 3.50 Stroke = 380ish cid. You could make 1200-1300hp with 23* stuff and a carb.