carb for the boys truck?

[57sailplane]

hey guys,

My boy who just turned 16 is driving now. I have been fixing this truck up for him. The little Rochester 2 barrel that is on a 305 CID started acting up real bad. It dies and barley starts sometimes and is a total dog. I have a Holley 650 and performer intake. I know this is a lot more power and i hope he will be responsible. My first question is am i crazy, I mean i want my boy to enjoy driving like i did. I really want to put an edelbrock carb on it for him when i can get one. They are way better on fuel and are more drivable. My other question is this have any of you ran the 500 cfm carbs.. my calculator says 558 is the biggest i should run on the 305. i was planning on a 600 cfm but the calculator suggest it as being to big.