A friend of mine use to have a 78-79 f--d 3/4 ton camper special with a main and aux. tanks. It had a switch on the dash that selected which tank and also switched the fuel tank sender so you knew how much fuel was in each tank using 1 fuel gauge on the dash.( Each tank had a fuel sender in it ) In your case, you could two valves, one for feed and the other for return. Maybe someone on here can say if Chevy ran two fuel tanks.
