340 w/ 650 double pumper ?

I run a 11:1 340 with an isky 510 solid, M1 single plane, 727, 3.91's and a 3200 stall with an 850 dp. on the street and it works fine for me. The vac sec carbs tend to be better for the automatics and better for street driving. I did have a 3310 (750 vac sec) on it at one point with a 484/284 cam and 323's with stock converter, same M1 and it worked ok except when it was hot (100 plus) outside. Tended to flood easier, once I installed a heat shield it took care of that problem. Would start fine and everything but gas mileage was down compared to a smaller carb. Didn't lose much (maybe 1 or 2 mpg) going with the solid cam, converter, gears and the 850. Really up to you but I wouldn't go higher than a 750 on a pretty much stock 340. And no Double pumpers if your worried about flooding some times and lower mileage. 650 if it's all stock.