Carb cfm with ported heads?

KD, I have a 408 in my car also with 3:23 gears and 2-1/2" exh but a loser converter (4k) and for a long time I ran a 750 HP on it. Ran great but I ran across a fantastic deal on a 830 annular so I bought it and put it on. I have a wide band A/F gauge on my car so I can tune it and when tuned the 830 did out perform the 750 on the mid to top end by a little bit, but not a huge amount. Boy did it kill the fuel mileage though (mine is also mostly a street car so mpg is of somewhat importance). BTW: my car with a 727 and 3500 converter and the aforementioned 750 ran 12.24 at 112. I went back to a 750. IMO the extra .10 quicker didn't offset the big mpg drop. If mpg isn't a factor for you go for the bigger carb and get one without a choke at all and put a wide band a/f gauge on it and tune it for max perf