Carburetor cfm calculator

Back in 1982, '71 340 Cuda street/strip, stock motor+ 484/284 cam, ally intake, small hdrs, 750DP, 3500stall, 3.55's/8x26" slicks, best was 13.28@101+, =301fwhp for weight mph, changed to an 850DP picked up almost 2 10ths. Put that carb on my mates ford Cortina with a tuned rover V8 (215ci) and 4spd who said that carb was too big for my motor and it went 2 10ths quicker over his 600. Forget the calcs if you want performance.