With some clever coding and dividing those 2 actions the times can probably be brought down but the main issue is that the time critical stuff is done in the loop, it should be real time...
The injection moment is in sync with the engine trough an alternator, I have a pcb with 4 IR transmitters on it and one with 4 receivers, between those there is a rotating plate with a little hole so at every TBP one of the receivers gets a pulse.
The casing with the PCB's in it can be attached to the throttle to create more advance when giving more throttle. (the above system has been used in the past by me and works flawless)
Nothing fancy, if receiver1 gets a pulse injector1 has to spray.