I,d get a new Carter mechanical pump for the cost and less headache.I ran one on my 410sb with 850dp,car ran 10,s.This was with the factory 5/16 sender into 3/8 fuel line.(yes I was schocked)LOL.
IMO, your pushingthe limit with the smaller line. While a 5/16 can actually surplythe feul needed for quick times, IMO, a 3/8 from tank to pump time is at hand.