Return regulator and line size

Hello all. I am looking for a return-style fuel pressure regulator. I am running a pair of 1964 Carter 3705 AFB carbs on a Stage II Ramcharger cross ram. I have a 1/2" line from my pumps up to the front of the car. What size return line should I run, and what regulator do you all recommend? I want to run a separate line to each carb off the regulator. Thanks.