That much NOS is going to be a block breaker! You can safely add 100HP to a nice 408 pump gas build, but not much more without over building the engine.
We're doing a pump gas 408 right now for CarCraft magazine and it should be between 450-500HP with RHS heads and hyd. comp cam.
It won't be out for a while but once we've dyno'd it I can help with combo (headers-intake-carb).
Most of them we build are 500HP and more but not under 5K.
Brian
