440 e85 carb size?

got a 72 dart with a 440 im running 91 gas right now and am thinking about switching over to e85 for many reasons runs cooler more power cheaper etc. ive got a 800 carb on right now and im in the ball park of 500-550 HP, my question is what size carb would i need to feed it on e85 ive done it to a small block but not a big block