1200GXman, fuel injection throttle body sizes and injectors are chosen to suit the horsepower target of the bike.

Bike engines make a lot more horspower per cc then pushrod dattos do, so if your motor is a fairly standard A14/15 or even a warm A12 then any FI setup from a 600cc bike engine will be fine.

If you have a worked A12 or mild A14/15 then look for a setup from a 750cc (ie GSXR) and for turbo application look for a setup from a 1000cc

ball park figures for late model unmodified fuel injected bikes are (roughly):

1000cc make around 145 rwhp (160 crank)
750cc make around 130 rwhp
600cc make around 110 rwhp

The keihin brand throttle bodies are used on nearly all brands of bike, yamaha, honda, suzuki, triumph etc.

Using a standalone fuel computer would probably be the best bet as I dont think the bike ones will be of any use to the average A series as the fuel maps would be for much higher RPMs