I have a 600cfm square bore vac sec on my 350 Buick the mtr has a 40tho bore with a mild torque cam,shift kit in the 350 turbo auto & stock 2.73 diff gears.
The problem I'am having is trying to work the jet sizes out currently they are size 66 that comes with the carb from factory. I'am finding it bogs down when I floor it & lots of black smoke pumps out the exhausts then the car goes very well & on long trips it runs smooth only if I boot it seems to pump to much fuel in. The carb is new as the guy from work I bought it off fitted a 750cfm on his 351 Cleveland & had the 600 that he sold to me for a very reasonable price.
Would fitting smaller jets only fix the bog down & how many sizes would you normaly try without spending a small fortune on jets & gaskets.