305 V8... 2 or 4 barrel carb?

[Pelon916]

Hey guys.. here goes another round of information leeching...

My truck has a 305 V8 with a 2 barrel carb (unknown make or model on the carb).
I don't know if the intake manifolds are stock, but I know they're nothing special either way, and they fit the small carb.

Anyway... I was offered a 600 cfm Edelbrock today and I'm not sure if it will help or hinder what I'd like to do with the truck.
I would like reasonably good gas mileage. I won't be towing much, if at all. I won't be driving the truck every day, so I don't mind swapping a little mpg for some hp. I also don't really hot rod at all.

Anyway... I guess I'm looking for opinions on the benefits of either a 2 barrel or 4 barrel on a 305.

Keep in mind that at the moment I have crappy stock exhaust manifolds, I will be switching them to ramhorn style soon.

If I put on the bigger carb will I most likely have to change the intake manifold or might it fit either size?

If I don't have nice exhaust yet will I not see a big difference until I get more flow on that end of the engine? I have dual exhaust now, and I plan on installing flowmasters when I change the exhaust manifolds.

Right now the truck has a 300 HP 283 cam but I don't know what valves it has or what the specifics of the cam are.

Um.. I dunno what else information might help me make a more informed choice about the carb.

The truck does run great at the moment, I'm just curious if a little more intake might help it run even better.