Everyone that i see here builing up a 351 uses a crummy combo, it's like they want a 351 but they truely can't afford it. With the right heads/Cam/intake, close to 500rwhp is very possible NA. But you can't use old ass junk yard heads, or heads meant for a 302, that is not going to cut it. It's not gonna be cheap. I've also seen nearly 450rwhp from a 347, which would likely make short work of the 450 in a Camaro, due to wieght differences in the cars.