Wiring harness and drivetrain swap - need advice

[tallon]

I am currently ripping apart my 2000 audi a8 AWD in order to swap it into another vehicle along with the engine and computers..
I am in the process of getting all of the wiring out of the car, so far it's all good to go except for the doors and all the wiring on the sides that route to the back.

What I want to know is, can I just cut all of that off and not use it? I can figure out how to wire the new tail lights and the new doors will have all newer simpler electronics so I don't need the audi's.
I wasn't sure if all parts of the harness would affect how the computer works if cut off.
There are things in the car I'm not even sure what they do! lol

I am trying to make this process easier so is there other parts of the harness I can cut off and not worry about? This car is going to be simple I don't need abs, powerseats, seatbelts, sun roof, interior lights or anything like that. Don't need the steering column or rack. The only thing like that I want to keep is the A/C system and for the car to run and drive. Maybe the IC, too.
Also I won't be using brake assist, either. Very simple build.

I basically just need to know if there are things that I definitely should not mess with even if I am not using it.

Any input is appreciated.
Thanks