Chuck, I read your response in the 51 post and I'm glad you have had a change in direction. It's hard to watch a fellow bolter fall into the money pit so advice is the best tool we have. Like you, I too came to the realization that the smart money goes to a "good deal" on an already reworked AD truck. That's what I did.
Back to the subject of the wiring harness on the 50. I still remember when cloth wiring changed to vinyl (or vinyl-like material). The new construction was a welcome improvement. Old cloth frays and it was easy to get zapped if you touched a wire that you thought was insulated. In the engine compartment, cloth wiring picked up oil stains so the wires had to be clear coated or protected. The good thing about vinyl is that the color lasts (except for cheap stuff). It's easier to troubleshoot when you have a problem. Insulated connectors are used with vinyl wires which helps reduce shock exposer compared to cloth.
A pre-made wiring harness saves time and makes sense. From a seller of wiring harnesses, labor is much more expensive than the material so unfortunately out-sourcing to another country would be the common convention for a US business. The problem with that is that the original manufacturer may not have a Quality Control. I have no recommendations for a seller of harnesses. I would make my own layout board and prefab my own harness. It may be difficult to extract the old harness intact but you would use it as a template. You could measure the existing wiring in-place but this needs to be accurate. You could also run a wire beside each existing harness leg, mark the wire, retrieve and measure to get the length of run.
