I have a 96 502 that started life as a mpi 415 horse motor. But now I have removed the MPI, and put a dart high rise intake, and a hp500 850 and I have emi exhaust on it. It also has roller lifters and a upgraded merc roller cam. I wanna make 500 horse. So what am I going to need to make 500? Im not sure I will even see a difference in MPH over what I have now...I run right at 70 gps now.

Procharger

What cam do you now have in it? Really the only difference between the HP500 and your old engine, is

CAM
INTAKE
CARB
EXHAUST
ROCKER ARMS

A good cam would be a 525EFI merc cam or similar.

so basicly all I need that is different from my motor and what I have done already is a cam and rocker arms..

Heads are different from what I understand.

what heads are on a 500hp? I know they arent aluminum...

Heads are the same. They are GM rect ports. The 500HP's might have slightly bigger valves.

It matters what cam you chose. "A cam" can make or break a motor. What did you put in it? Did you verify that your stock lifters will work with the new cam's lift?

Your heads are the same as an HP500, and your valves are the same size. The HP500 does have upgraded valves, but not for more power, they are for better longevity.