Well, I got the 91 degree C fan switch but failed to check this board and have no idea as to why I picked that switch. I think my reasoning was that when my temp gauge was at that point (exact middle) is when i wanted the electric fan to kick in. See this post:
http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/t,358682/