My bad. I said 1/4 pipe but it's 3/8. Here's what I recommend. Rather than restrict it at the pump, get this.
DODGE Carter M6270 Carter Strip Super Mechanical Fuel Pumps | Summit Racing
Then all you need is an easy as hell to find male 1/4 NPT to female 3/8 NPT fitting and a male 3/8 NPT to "whatever size" ( I assume 5/16) hose barb. That way, you have a REAL HP fuel system from the pump to the carburetor and can upgrade the pump to tank line at a later date. What you're doing is trying to connect race bred stuff to stock stuff and that "generally" doesn't work so well.
