...I have the fuel pump drawing fuel from the R/hand tank up to the fuel rail and the return through a cooler into the L/hand tank if I do not link the tanks I could end up with one empty tank and one full tank and no fuel at the injectors ;-( but I am open to any ideas at this stage once I cut the holes in the tanks there is no going back!
Depending on your fuel flow here are two 6 port valve options that will allow you to run off of 2 tanks and return to the same tank as you draw from. Which In my mind is the safest way to go, no risk of over running one tank because of a failed valve, plugged line, or carelessness.
Pollack 6 port valve Groco manual 6 port valve If I ever run dual tanks on my truck I'll use the Groco. Wish I had found them when I was plumbing my fuel system, would have installed one from the start.
Grigg