This is not an option. It comes standard with the 460 option.
The fuel pump in the tank is a low pressure pump capable of 25 gph @ 4.3 psi. It sends fuel to this little gizmo by the carb called the vapor separator. This works by pressure. What the carb doesn't need, it sends back to the fuel tank. The idea behind this is it keeps a constant supply of cool gasoline available to the carb available at all times eliminating vapor lock and other maladies.
Remember, these trucks were built to work!
Good Luck!