Cross ram carbs

wondering what carbs would work best for a 472 hemi with crossram..as far as cfm's. I want manual choke and I assume mech. secondaries, and I found 450 cfm hollies for $289 each. Would that be a good route? Its mainly a street car, and I think 900 cfm would be fine, as I have a 850 single dp holley on it now.I have seen that the oringinals had 770 cfm I believe? Sounds like alot! Just looking for suggestions, as I get lost in this kinda stuff.. thanks!