Tomorrow I'm going to take a look at an '89 e34 without engine to see if I can salvage some parts. More specifically I'm planning to swap the interior from grey cloth (mine) to beige leather (donor).

And then the usual like steering wheel, rims, electrical windows, etc. How hard is life going to be attempting all this transplanting? I'm looking for some how-to advice as well as cautions.
Like: are the electricals superhard? I get the impression most of the wiring is already there and unused. Am I right? Especially curious about wiring for electrical seats/windows (cause mine has none of that).

I would like to find the thread about an interior swap that had pictures and everything where the poster also refurbished the headliner (mine's sagging).
I'm thinking this would take me a week. Does this make me an optimist or a pessimist?