A 94 isn't much carburetor for a 471 at 165 CFM each.
The total CFM you need depends on (of course) engine size, but also how much boost you expect.
The usual CFM calculation gives about 337 CFM at 5,000 RPM.
Math: if you have a 235" at 8 psi (and atmospheric pressure is the usual 14.7 psi), your pressure ratio is 1.544:1.
For draw-through use, the N/A CFM is multiplied by the pressure ratio, in your case the result is 521 CFM, much more than your 94 × 2.
This means you will have quite a bit of vacuum at the carbs at WOT.
Do these have vacuum-operated power valves?
