If you haven't settled on a fuel pump set up, you can do an intank one pretty small if needed. I used a ninja650 regulator and a sportster 1200 pump with a home made sending unit. It required a 1.55"×2.1" hole to be cut in the tank. Holds steady at 41-43psi all the way to redline on my XS, no leaks, internally regulated, fits a tiny tank. Just throwing it out there to show the possibilities.
