Greetings folks from Florida, I have just purchased a 460 Ford powered Jet drive boat. The carb is a double pump Holley with mechanical secondaries. The choke air horn and choke has been removed (I assume that is where the model numbers were stamped). How can I tell whether this carb is a 650 CFM or a 750 CFM carb??? Are the venturies different size? Any info as to how I can determine what I have is greatly appreciated. Thanks in advance for any and all feedback,