Well when choosing a carb or intake and making it useable can be tricky. Using a smaller bore in the carb improves the fuel draw, as the bore gets larger the engine gets less able to draw fuel well. So they have to compromise it so that it can have decent fuel draw and not be too picky on fuel tank location and fuel line length. A big bore carb may cause the engine to be very sensitive to fuel tank location and it may have to turn higher RPMs to get the fuel draw to be acceptable, and then in a particular airplane it may not be very flyable.