New fuel switching valve

All the original fuel lines and switching valve was gone on my 86 F150 when I bought it. The pickup has duel tanks and originally had a 5.8l carb engine.  It currently has a 5.0l engine with a carb and the PO had installed an external electric fuel pump and 3 port regular only hooked up to the rear tank.

I want to keep the 3 port regulator and keep open the option of going to EFI. I got two port fuel senders for external fuel pump and a Standard 6 port switching valve to allow for a fuel return.  The switching valve instructions show that the power and ground need to reverse to make the valve switch positions. After some investigation yesterday I found the pickup’s tank selector switch is just On/Off for the power to the switching valve.

I want to keep using the original tank selector switch since it is in good working order so it seems I will need a DPDT relay to reverse power and ground for the switching valve. Has anyone done this before?  If so, what relay did you use?  

There are a couple of options, one is to find a tank selector switch for a truck with a 460 and hot fuel handling package. It is a 6 terminal switch that does reverse the polarity to the 6 port switching valve.

Go here for the 7.5L selector switch and gauges Page 96 is for a mechanical pump and page 97 is for in-tank pumps for a carbureted engine (the selector valve switches the senders). https://www.garysgaragemahal.com/fuel-tank-selector--gauges1.html

The other option is to use two Bosch relays, one controlling each side of the valve motor. Use terminal #30 (Bosch number) for each side of the motor, on one relay connect pin #87 to power and 87a to ground, on the other, pin #87 to ground and 87a to power. Wire the relay coils in parallel so they both activate at the same time. If you go with this option, I would mount the relays inside the truck so they don't get wet.

For a DPDT relay, look for one for a power antenna.