Sorry, I did not see that the car has been over revving. How high is it actually revving to? You could be suffering from a severe vacuum leak, causing the engine to run lean. That can cause the vehicle to overheat also.
At least we know that you have an electric fan now
Most likely, the wire has been fried by the exhaust manifold. I have seen instances when an ECM is failing, that the engine will start to rev up high, but if you aren't sure about the routing of the vacuum lines, it is probably a vacuum leak.
I will try to get that scanned and sent to you. shoot me a pm with your email addy and so i can try to send it to you.
To better help others help you, it would be advisable to edit your signature to include all possible info about your car. IE: 86 L69, mods listed, and any other work you have done. (See mine below)