Basic 318 Mods

Wish me luck as I'm going to be checking out a couple of duster's next week. I'm only asking these questions as a quide, both are 318 cars but one is a 2 barrel. Once the car is home I'm going to check it out completely and if everything checks out okay I'd like to do a 4 barrel swap and was wondering what size carb and intake manifold to use. I thought about a better coil and module. A curve kit and a good dual exhaust system. The car will be a cruiser only and probably the engine will never see more than 4500 rpm's. I'm open to a stall converter and a different gear ratio. Maybe even a mild cam.
My guess is you want to hear go with 500 cfm carb which would be just fine. 600/650 leaves room to grow. Either will work.