Yeah fueling is the big part, needs to start with a basis that at AFR is 14.7:1, then calculate approx what air quantity the engine is likely to inhale per minute, thus being able to work out how much fuel in theory you need to mix with that for it to burn at ideal. Then dividing that amount by the RPM would give you the amount of injector pulses per minute and you would have to work out the amount of fuel to push through per pulse. You could probably build a fairly uniform table for that. but alot of head work and I am just throwing the idea out there before I start trying to do the computations.
to Fire the injectors I believe you can use mofsets, the ones in computer PSU's handle a fair amount of juice so I am sure they will be fit for purpose (I had been reading on these else where on the internet). Throttle position sensor is just a pot, the duel bike throttle body I happen to already have has one on the side. I need to invent an engine temperature sensor as being aircooled it doesn have one!
I didnt plan on using EDIS, theres not the room for the EDIS pack considering how big they are, I was just going to trigger the existing bike coils using some power transistors/mofsets/something the same way electronic ignition systems used to work, meaning the arduino would just need to be a small switch to earth. As for trigger wheel I was thinking of building my own optical wheel setup using something like the parts out of a mouse, my only issue there would be the amount of heat it was subject too, making a hall effect sensor more useful, once again though space is a limit.
Wiring and connectors, well I have a complete loom from an early 90s mitsubishi, theres more than enough wire and connectors on that to use for this project!
Data logging wise, the arduino is capable of that using SD cards and I guess to some extent the purpose here is that you would need to data logging to start with, so build the engine and fit all the sensors, but have the engine running on carbs/points to get some data together, then tune a table for the running.
I havent really thought it all through yet, the biggest thing is trying to get my head round the amount of instructions the arduino could do per second, as relatively speaking there isnt tons going on, its just the speed at which it happens like an injector having to fire 250-2500 times a second to get the fuel in (think thats right but there may be a different way of doing it). I may be barking up the wrong tree a little, but at least I have some ideas and a starting point I think 