I'm doing the same thing for my AU2.
The following docs will give you all the information you need.
, is for series 1.
pins for AU
, is simple version. (but unsure for which version of AU)
has everything you need (probably the only one you need to read). At first it sounds complex, but really all you gotta do is swap over a few pins, and change the oil sensor on the engine (like $5, 2 wires..) and she'd be good to go.
Hardest and most dangerous part is changing the ROM change over, which has the KM's on it...(which you must do or face like a $10k for rolling back the clock..)
My plan (after I buy the next one which pops up on ebay) is to just make a little adapter, so when it comes time to actually ripping out the dash and plugging her back in, no wires need to be soldered. Just put the adapter on her and she'd be good to go. Although, saying this, I've never seen the back fo the dash, so I'm not sure if it's a socket type plug, or if all the wires are just loose...