Dwayne didn't like the heads. No raised roof and stock length fat valves. I worked at the dealership and got a great deal. And frankly at the time like 12 to 21 ? years ago there wasn't a lot available. The Chapman's were but out of my price range at the time. 528 cubes matching MW port single plain M1. I picked the cam that fit Dwaynes recommendations. Less that 670 lift and as much duration as I could get away with. Mopar P5155616 657/659 308/315 275/282@50 Apparently it works. Even the dyno operator (a known Chevy guy) seemed surprised.