Here's 617 HP with 11~1 (10~1 is max for shootout), ported Indy SR-1s, & Hedman stepped race headers. It's bored to 4.195", which can use Chevy 400 smallblock O.S. pistons & H-beam rods.
Same engine with 10~1 peaks @ 593 HP & 510 ft/lbs tq., adding an 1150 Dominator adds 11 HP & 6 ft/lbs.
Bumping the stroke back up to 3.68" yields 586 HP & + 20~40 ft/lbs of torque below 6500.
(according to Dyno2000)