dynoed my 416

I dynoed my 416 on saturday, 465 hp/510 torque on pump gas, 483/526 torque on race gas. It has slightly worked edelbrock heads, 236 @ .050 hydraulic roller, .550/.570, edelbrock air gap, tti headers, holley ultra 4150 race carb 750 cfm worked over, flows around 830 cfm. I think the carb is too small, as a 950 proform out of the box the dyno operator had lying around made about 10-12 more torque and hp than mine without even any tuning. I also think my headers are on the small side, I'd like 1 7/8 but I dont think anything else will fit nicely. Car is '75 duster, 3.91 gears, 727 manual valve body, 3500 flash stall 9.5 inch. What do you guys think. I think it should be pretty wicked for a street car. Any suggestions before I drop it in? Any 1/4 mile predictions.

-Will