I believe fuel lines are 5/16.
the dealer should carry them...if not GPR or GAP should have them.
Also Summit carrys all types of shit believe or not.
Ya, IIRC the fuel lines are 8mm, which is almost the same as 5/16" For brake lines, it can be a pain with the double flairs. I've always just yarded some lines, and rebent them for my application. I'm assuming yours are getting rotted out?