I'll probably get flamed for this but...
The 950 HP works great on a 454 but You don't need one with that set up. Smaller carb that is good would feel faster on the butt dyno because those heads are hurting your low end torque and the camshaft is DONE way before the heads .
I guarantee you that you would be happier if you change the heads to oval ports. You don't have near enough motor to need the square ports.
jmo