A faulty regulator or shorted alternator could have caused the problem but more likely it is the questionable wiring or a bad ground.
I would replace the voltage regulator (it's probably fried too) and at least have the alternator tested.
Depending on the amp output of your alternator (anything over 65 amps) I would recomend a voltmeter over a ampmeter as well. They are safer and more usefull.
I don't think this is exactly what you want to hear but if the wiring in the car now is a butcher job your better off buying a universal wiring kit from a company like Painless or maybe a harness from one of the other Cobra kit manufacturers.
You are lucky all you have is some burned switches a gauge and some wiring.
Your entire car could have burned to the ground.
Oh yeah, for petes sake, put a ford engine in the car, please
--Mike