If you want to eliminate one of the tanks is should be a simple matter of removing the crossover lines, the switch valve and running the fuel lines directly to the tank. It will be MUCH easier using the Left (passenger) tank though as the lines are already ran down that side of the frame and from the factory the single tank was on the Left. As far as the wiring to the switching valve, you should be able to trace it back to the switch and then over to the firewall to the instrument cluster. Outside the firewall before the fuse box should be a plug, just use the wires you removed for the sending unit to go to just one tank.
What are you hoping to accomplish? Simplifying the fuel system or?