It can be done. The hard part is finding throttle bodies that fit, and getting a crank trigger wheel that can be used for both ignition and fuel. I have had all the parts but never the machine shop time to mod my pick up wheel cover, nor could I find any throttle bodies that would fit my engine.
Here is a list of things though you would need to go full custom for a FI conversion
Walbro 255 in-line fuel pump
either a rising rate adjustable FPR or just an adjustable FPR (fuel pressure regulator)
Crank trigger wheel
coolant temp sensor
Intake air temp sensor
Liter bike injectors
throttle bodies that fit
misc fittings and clamps
wideband O2 for tuning
fuel pressure gauge for setting the fuel pressure
O2 bung welded into header
And a laptop for setting fuel curves.