My experience has been that a 750CFM seems to work very well on a stock (marine) 460 (320HP) in most cases. I wouldn't, personally, run under that in a jet boat since we run them in the 3500-5500 rpm range all the time. The max rpm rating on a standard Hardin Marine 460 is 4600, and a carb smaller than 750 CFM definately helps keep the RPMs under that in small, light boats. They came (At least the unmolested ones I have seen or had) stock with a 650 CFM or 700 CFM and one of the first things swapped up to a 750 or above on any you see these days.
Probably more a warranty deal than anything else on those. They'll spin well over 5000 handily in stock form. Kinda weird that Ford threw on their best square-bore CJ manifold (which is kinda hard to beat from the aftermarket, to be honest) and Hardin stovepiped it with a small carbueretor.
Mildly warmed over to some pretty hot machines will appreciate and wake up with an 850, however, and likely not "over-carb" a stock one either when tuned properly.
Start getting radical on cams, high compression, stoker kits, headers, intakes, etc, you start to get into 950 CFM or 1050+CFM Dominators pretty quick.
Ray
