3/8 vs 5/16 fuel lines

Lots of good ideas and you guys helped me a lot in the past. I did block the tank vents but changed it like the older ones from the fill tube down to the chassis. I put the electric fuel pump in for easier starting. Manual choke too Put in a fuel line pressure gage and it reads 4 to 6 at idle. I'll move it so I can see it under load. I'll check secondaries when I get home 600 miles left. If it makes that much power on those little primaries I'll be happy when the secondaries come in .It should be making about 400 up Thanks all and Merry Christmas