serious street power.

It seems as if they are figuring the 512 with a .055 overbore (somewhere around 511 actually). I guess they advertise by the maximum cubic inches you can get with that kit. As far as the cam, I would definitley not recommend a huge one. A big cam does not equal big power, especially for a street car. All you will get with a big cam is a bad time on the street. I would say give Hughes a call. It seems like they tend to make their cams more for torque, which is what you need in a street car. Had them recommend one for my 440 and I am very pleased with it. Between 500+ cubic inches and a Hughes cam, I would say you will have a very torquey, fun street car.