72 Scamp and 440

Well im not looking for numbers. Id like a good pro street type car. Something with 500+ H.P. Its a /6 car so im not looking to go original with it. Ive always liked the look of tubbed cars so thats in the works. No blowers or nitro just naturally asperated. So far what ive seen on here the headers are the biggest problem with the swap. So if the 9inch rear is a bad idea do I have to get a 8 3/4 specific for A-body? Also how close to the specs is a Scamp to a Dart? Are they pretty much the same?