Re: control fuel maps in EECV/IV
Sounds like your idea is just to make the fuel map adjustable, yes?
If so, why not just get an AFC, splice it in to the MAF wiring and adjust away?
If there are other reasons for doing trying to get a fuel only ECU you might have to explain further.
The other thing to bear in mind is that both the existing ECU and new fuel only ECU will need to be connected to all the relative sensors, to do this properly you would need to fit inline diodes into each of the wires to prevent possible false reading caused by backfeed from either of the ECU's. This in itself could work out to be fairly costly.
You can get a Wolf 3D supplied, fitted and tuned for around $3k, in my opinion that would be the better way to go. Doing this will also allow you to get rid of the MAF and just use the signals from the TPS and MAP instead, therefore less intake restriction, more power.