Hi Rickard
Welcome from me also. I will also be watching your build. I have an E30 Sportster built at arround the same time as the one that you have pictures off on your Flikr site.
The best advice for the electrics is to make sure you photograph and label everything carefully when dismantling the doner. I re-used the E30 wiring loom including the fuse box and all relays. I spent an entire winter season identifying all the circuits and stripping out everything not needed. As a result the electrics went together easily with everything working first time. Even the engine!
You can see my build here.
http://myweb.tiscali.co.uk/martinclan/
Personally I wouldn't use the ABS. It just adds complication to what already is a relatively complex build.
Cheers, Robin