opinions on carb for mild 400 mud/dirt racer

Im looking to buy a new carb for my budget mud/dirt racer toy and would like to have some opinions. The vehicle is a 89 ranger long bed body adapted to a 79 f-150 4x4 chassis with 3.50 gears running a c-6 automatic with a 1800 stall converter running low range in the transfer case. Its got a 400 with stock bottom end, 4v closed chamber heads, offenhauser dual port intake, headers and stock ford ingnition. The cam is a lunati voodoo #62502 with 219/227 duration and .540/.552 lift. I was running a 600 holley vac secondary that run good but had a problem with the idle circuit so i tried a 670 holley truck avenger that my buddy had. The truck avenger felt stronger than the 600 but had gremlin that i couldn't get out. The max rpms the motor runs is 5000 where it shifts. The holley carb selector says a 600 is what a 400 needs that runs max 5000rpms. I am considering the holley 1850 600 vac secondary and the holley 3310 750 vac secondary. I want good throttle response out of the hole but is the 750 too much carb for what im doing? The races are 150ft length track at wide open throttle. Thanks for your opinions.