5/16" Fuel Pump Inlet for 340?

I'm putting a 72 340 in a 68 Dart. I replaced the 5/16" fuel line with a 3/8" line. My engine builder put a stock replacement Carter M6866 fuel pump on the 340. The M6866 has a 5/16" inlet on it. Should i put the 5/16" sender and fuel line back on the car, or do I need a different fuel pump? I noticed this when I tried to connect the fuel line to the pump with a 3/8" rubber fuel line. Thanks.