I would think a 390 would be the perfect size for a street driven 283, but no your 600 cfm carburetor is not to big. Keep in mind it is still only a 300 cfm two barrel until the back two barrels open up. That will not happen until the motor is drawing enough manifold vacuum to open the rear barrels.
If you are spinning the motor high enough frequently enough then that carb will be far too small. Chevrolet puts a 780 cfm four barrel on their 430 horsepower 427 yet install an 850 cfm double pumper on top of the race ready DZ application code 302 RPO engine code Z-28 that has mechanical tappets to go along with the mechanical secondary barrels and the engine will routinely spin to 8,700 RPM (it's shift point).
I would think that there are literally thousands of those carbs on top of a 283 or even a 327. I know that it is the most commonly encountered carb size at a flea market. I used to be able to find and buy those carburetors routinely for twenty five dollars used.