Carb too big?

The math works out such that a 225 cubic inch naturally-aspirated engine at 5000 RPM is lucky to be capable of breathing about 350CFM, assuming it has the right cam to let it even breathe somewhat efficiently at that RPM (think 225+ deg @ .050 lift) in the first place.

Whoever had that car previously must've subscribed to the mind-set that bigger carbs magically increase an engine's displacement and RPM band.