The lines coming out of the tank are 10mm (supply line) and 8mm (return line).

 

The supply line is the forward tube and the return line is the rear tube.

 

The following items are noted for fuel lines and clamps:

5/16" = .3125 = 8mm ID and fuel lines of that size are 13mm OD

3/8" = .375 = 9.5mm ID and fuel lines of that size are 15mm OD  This creates a snug fit over the 10mm (0.3937") fuel supply line at the tank.

The OD should be your guide for the fuel clamps

The supply line should be E85 gasoline compliant, but it is NOT a pressurized fuel injection hose because it is before the pump and it will be a bit more flexible to make the bends..

Hose Clamps - 13mm (about 15 of them) and 15mm (2 of them for the supply line to step-down filter or 3 of them for larger supply line to the rear.)

 

I used Stainless lines that I bent myself and flared with a heavy-duty flaring tool.  The lines at the engine were supplied by Racer Chris at Tangerine Racing.  Remember that stainless is a tough thing to bend and the line in the engine bay that come up from the engine shelf have multiple bends that would be very hard to do by hand.

 

My car is using a 1974 fuel injection setup with the three hose pump.  The 1975-1976 cars used 8mm lines in the tunnel and a front-mounted pump that was just two lines.  Also, the wire supplying the 12V to the pump is a higher gauge on the 75'-76' cars to get the juice to the front, below the tank.  Those two years also have a small tab for the ground welded into the front fender near the wiring harness (driver's side).

 

 

Stainless lines in engine compartment: