corrected my first post so that the link was clickable.
as to dialling the EFIE in, it was pretty simple: the manual has the info, but the big help may be the video on youtube (which I had to watch a few times because he got me all confused with the alligator clip jumper wires) of calibrating/dialling it in.
what you have to keep in mind is that the computer is looking for a
waveform, a consistent voltage swing, so for me, I had to find the balance between the EFIE and the MAP enhancer, which was (surprisingly, since I just dialled it in by ear and feel rather than with any type of meter) very close to where it sits now. I've done a number of drives through the orchards and vineyards just outside of my small city with my voltmeter (analog style, with a needle that swings rather than a digital one with numbers that autorange) to see that the needle was indeed swinging rather than pegged. Yesterday afternoon, I got the balance (between EFIE and MAP) about as far as I care to take it; I was able to trim fuel delivery at idle back to almost stalling - the tach was below 500 rpm (factory idle is 550ish).
For you with the v8 and multiple EFIEs, I recommend a staged approach: what you do to one bank, you apply to the other, and then repeat, taking small steps. maybe 50-100 millivolt adjustments to the offset at each step, with a drive between adjustments. you'll know when it's not right or if you've gone too far.
ADDENDUM: here are good articles on o2 sensors, their operation and what the computer is looking for from them. Preston, you should go and see what they have to say about the waveform I mentioned above
OXYGEN SENSORS: HOW TO DIAGNOSE & REPLACE
Wideband O2 Sensors and Air/Fuel (A/F) Sensors