I thought you'd at least make 450 hp. if you were on a dyno, that wasn't so conservative you'd make 450 horse I bet. I built a 476 with edelbrock heads, a 219° at .050 cam and 9.0:1 compression. it made 482 hp and 533 tq. I wonder how much of that difference came down to the beads. I'd like to know how good the speedmaster heads are. I think that will be a great motor for your truck. its gonna be a big difference from stock for sure.
