I remember when I did this exact same thing to that '69 2002 I had (that I sold before finishing). And I agree with Rudy. Carefully take out all the wiring. If it's in that bad shape, put it down on the floor and pull out the soldering iron.............. start replacing that bad parts. Electrical system is important and considering you're going to all this effort, may as well take the time to finish everything rite while it's all apart.
Rite now I'm doing a complete tear down and restoration on an E30 M3. Tear down is now finished and I'm in the process of rebuilding it all. The '69 2002 was a hell of a lot simpler and yet the E30 M3 has been more enjoyable........... as it was a Texas car with no rust or seized up parts. I also had another E30 M3 Canadian car for parts and I cursed a swore like mad at that car as she was a biatch to tear down for parts cause everything was Canadian-ized............ rusted, seized up, dirty, etc, etc. That pig got me cut up and bleeding more times then I want to remember.
Anyways, good luck with the project. Hope your garage is insulated !!!!
Current : 2013 Mini Countryman JCW
Past: '88 E30 M3, '69 BMW 2002 Ti, 2000 328i, Audi A6 TT, BMW X5 3.0i , Audi A4 1.8T