It might be a silly question, but why not return the fuel to the right tank? Using an elect. bypass swith. you could do the same to the left tank, you may have to use 2 switches. You could rig up the left fuel gauge to a relay that would turn an elect. fuelpump on, to pump it back to the right tank, then you could conect them at the top. Less chance of a leak that way. This way you could only fill one tank though. In the early 70's toyota used a small bypass valve just after the fuel pump so when the carb. float was closed, it just went back to the tank. I did this to my 53 1/2 T and it works. Not sure with a fuel rail. Just some thoughts. I like the way those tanks fit.
