Installing a fuel tank switching valve on a truck that never had one?
 

I want to install a fuel tank switching valve or equivelant on my truck so I can switch to my drag up, (may have cheap red fuel) and then back if I need to, then there wont be any contamination in my truck tank, just whats in the filter and fuel lines. How much fuel returns from the return line, gallon a min, gallon an hour? Can the fuel return be ran back up and into the drag up or is that too much of a climb, what pushes that return fuel?