Carburetor cfm calculator
Run what ever size/cfm carb you want.
Can you run a smaller carburetor and still turn rpm's, sure. You'll just effect the torque output. You can cruise a 600 on a 440 or 500 on a 360 etc... if you want some more umph for passing but ultimately focus on gas milage...use a smaller 4 brl than optimum for max power. 750 or 390 lol you decide. 800 something is a wash for low rpm drivesblility on a 340/360. 950 have smaller venturis...