That cam has the same specs as a CC 280 Magnum, a cam that I run in my 383. Good choice! With AFR 190 heads, mine made 450 hp and 468 ft. lbs on the dyno. So I would say you are within 3- 5 per cent of your hp number, but I would figure that 3-5 per cent less than 455 hp. Most DD Dyno numbers are a little on the high side. If your engine runs anything like mine, you won't be able to wipe the smile from your face!