NASCAR guys make a ton of power with 390 cfm carbs, of course they have a few tricks but they are really 390 cfm carbs.

I think a 500 cfm carb will work just fine on a street driven 440. The power would be down a little bit at WOT but probably not more than 10 or 20 hp from a 750 or 850 carb. This is assuming it is a street motor with a mild cam and pump gas compression.