Andy, your inspiration is driving us, however i am sure you said AGU ECU as the only flashable A4 ECU is the very late DBW and thats not an option for the AEB engined car.
I am gonna persue this a bit and see where it leads, i already have the 1998 to 2000 loom and ECU on mine and its a chip job to tune, why they don't socket, i don't know.
Whether this was what you said or nt, it actually makes sense to me to try, i am sure with the correct ECU connector spliced into place that the dash can be matched to the ECU and it will run. I have checked the wiring pin out and it seems the same bar an extra for a clutch switch