Bruce-
I agree that if you use vacuum secondaries you can use a bigger carb or multiple carbs with way more cfm than the engine can ever use, but again the question is what is the point? If an engine can only use 700 cfm why stick 1150 of cfm on it? The extra cfm is wasted and you may see a drop if in power/torque and throttle response on the bottom end. (Explained below.)
As I am sure you are aware, when you use a bigger carb, the velocity of the air/fuel mixutre coming into the carb is slower than it would be in a smaller carb, which may lead to decreased throttle response or a slight drop off power/torque on the bottom end. (To your question, even if you're only running on the primaries, the size of the venturis are smaller in a smaller carb and larger in a larger carb, so regardless of whether you are running on only the primaries, the velocity of the air/fuel mixture will be slower in the bigger carb). As I mentioned previously, if you are drag racing and running to 7k all day long, then you really shouldn't care about a slight drop off in the bottom end, but if you are driving on the street and keeping the revs under 6k most of the time (where most cobra replicas are) you will likely get better perfomance with the slightly smaller carb.
That's all for now. And no problems with dander, just a freindly discussion.
