If the stock ECU is in use, the answer to that is 'none' except at idle or WFO, when in open loop, or if you go way to far with spring adjustment, which will kick it back to default open loop as it won't be able to control things in closed loop, so will revert.I could mess around with the AFM spring and tell you guys how much you are actually affecting it with so many clicks of the spring tension. (Air/Fuel ratio)
I presume you're familiar with dealing with a vacuum balance chamber for use with a MAP sensor then? (the sensor really, really doesn't like that pulsation/surging that occurs when all the intake runners can't be tapped)
Coil packs? So you'll be using a Hall sensor or the like to trigger, or have you something else in mind?
As you say you're used to the motec, and realistically most all of the systems operate in some simular fashion, (measure manifold pressure, measure air and water temperature, known values for injector flow plugged in by some means, proper fuel pressure, crunch numbers, squirt fuel), is there any reason to think you could get close using numbers you already know to start with?
I'm not talking exact obviously, but a decent close start to work off, or at least get it to fire up quicker than a hunt and seek type method.