Maybe run a hose from the airbox to the fuel tank vent line? The tank would see vacuum though most of the time, not sure if that is a good thing. My bike has no pump, it's gravity feed.
If I was pushing much pressure I could see a need to change the pipe to make sure all the mixture that is forced through the cylinder out the exhuast port gets shoved back in at the right time. starting to sound more complicated than I thought.