For an "on the cheap" deal, use the manafold you have. No! Really! Use a roller of 250+ deg at .050 intake and 260 at .050 exhaust. These heads when properly ported can make 550-600 HP without the blower. The Chevy heads use the same exhaust port for the peanut ports, oval and square ports, that means that your exhaust port ratio to intake flow is good. If you can't make that rig run 90, shoot yourself. For further info call me. TIMINATOR