Mine is well over +700 on pump gas, but the cam I use can be a pain in the a$$ on parts and its +.060 and a 4.15 stroke. My heads flow right around 400cfm, and it makes the hp and the torque, just the spring pressures can be a pain.

My engine builder has one that is 657hp and is street driven runs 11.1s in a very heavy street car on drag radials and has a very mild cam, good flowing heads, and we have been kicked off the track for only having a lap belt and going over 122mph on that 11.1 pass. It is also a 4.15 stroke crank motor displacing 477 cubes.

My only 426 +.030 made about 580-590hp and was very streetable. The best street intake we have tested to date is the Ray Barton single plane...and around a 950 carb. The cam and heads will cost more than the stroker crank to make the hp and torque your looking for. I suggest going the stroker route....