I can understand how fire damage could render the rear wiring harness unusable. But my first choice would be to try to repair it as others have said. If that’s not an option Wilkinson now manufactures the wiring harness for the engine bay.
The wiring under your dash is probably in about the same condition as all the other Panteras. And thus very workable. Since the car has been sitting it would be advisable to simply remove the fuses, clean them and their sockets, and put them back. Or just use new fuses.
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