I have a similar motor
Demarques. I just finished a 9.5:1 383 and had it dyno'd this afternoon. I went with AFR 180 Street heads, Comp Cams XR270HR, but with a 600 cfm Edelbrock 1406 and a Performer Air Gap. We had to change the jets, rods and springs in the carb to get the right air/fuel mix, but the results were great. 422HP at 5200 RPMs. 463 Lbs TQ at 4300 RPMs. Still had vacuum at WOT so a larger Carb will get you more HP. The motor is a Torque monster.
I have a 700R4 with a WOT Shift point of 5100 RPMs. You shouldn't need a new Converter. The more powerful motor will create a higher stall in your stock converter.
Last edited by 67L; 02-02-2013 at 12:14 AM.