Carb suggestion for 360

Depends on the usage of your car. Engine seems like a good street build. What is the compression, converter stall and upper RPM going to be? A smaller carb will give you better air velocity and throttle response and possibly slightly better fuel economy. Any thing from the 600cfm mentioned up to a 770 Avenger will work. Your intake will flow more than your going to use, based on the rest of the engine specs, so the additional flow a bigger carb provides on the top end probably is not needed here. With your specs I would stay to the smaller end of the scale unless you are planning on a bigger cam, head work and compression (higher RPM operating range) in the future.