If you're using the mechanical pump you could run the return line back to supply just before the fuel pump, it would then recirculate fuel from the regulator and use only what is needed at the carb.

1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy