Take a look at Honda's TRX420/500/680 fuel injection systems.
Throttle body with combination TPS/MAP/Baro sensor, external fuel pump that puts out 50 psi and is contained within an aluminum housing which is gravity fed from the fuel tank.
I don't remember what the bore size is but it's feeding a 420-680 single cylinder four stroke.
Who knows, there should be plenty that have been totalled ..............
That should take care of the hardware.