I have a 4.0L Whipple on my GT. Torrie McPhail conservatively tuned my car to 737 rwhp and 668 lbft of torque. My stock fuel pumps hit 100% duty cycle at 6500 rpm. That's with 19 pounds of boost.
As others have stated, you can get similar power levels from the 3.4L Whipple... if you can find...