FiTech EFI system

Looking for input on the fuel line sizes people are running. I am running an in tank Walbro pump and have 550 HP and torque. I was considering using the stock 5/16 fuel line as the return with AN 6 from the throttle body. Is this sufficient for the return?

What are people using for size and line type for the high pressure line from the tank to the throttle body?