Lots of people use 600 cfm carbs on 460's but if you think about it:

604 CFM on a 302 is 2 cfm per cubic inch
920 CFM on a 460 is 2 cfm per cubic inch

Just about everyone is running 600 cfm on 302's, yet how many people do you see running 900+ cfm on a 460? I'm beginning to think 750 cfm is in the ballpark.