The proper CFM single carb is ALWAYS better than multiples. The more carbs you add, the potential for problems increases by a massive amount. Intake manifold and cylinder head design has a lot to do with how efficient a multi carb setup will be, and the stovebolt Chevy design sucks like a vacuum cleaner- - - - -GMC heads and manifolds are only slightly better! Since both types of head have only three intake ports, the best choice for a multi-carb setup is a carb for each port, one that operates efficiently at the desired top RPM to supply sufficient volume for ONE cylinder. That's because each intake port is only fueling one cylinder at a time each turn of the engine, due to the 1-5-3-6-2-4 firing order. More carburetor CFM than that makes the engine only perform close to properly at wide open throttle, max RPM. The laws of physics are not "suggestions"!
Jerry
