The engine damage part of your story sounds fishey to me. I have never heard of a "too rich" mixture causing any engine damage. It will cause carbon build up, but damage? I think not. If the fuel was so rich as to "wash all the oil off the pistons and caused the rings to burn" I doubt it would run at all. You would have to have a serious flooding with all that fuel and things dont ignite when there is that much fuel.
I would replace the wiring harness first, and then test the engine and see what condition it is in. One step at a time.
I got too many cars!! Insurance eats me alive. Dave
78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k