I have driven a b can car with gr40p heads and cobra intake. With factory 3.08s it pulled hard up top, and got rubber into 3rd. Stout combo that car was.
All hail the almighty Beast 303 cam! All joking aside, I think the stock cam is a better performing cam, especially for a street drive car with stock heads. If you really want to the change the cam, go with the CompXE258hr cam, aka stock HO cam on steroids. Later on if you decided to install gt40p heads, you will have a torque monster, but it the power range will only be until 5300 rpms, that's why I recommend it for automatic applications (AOD's). For a 5 speed, the compXE264 would be better.