Starter clicks using the key, engine starts by jumpering the relay

I think you first need to trace out all the circuits as mentioned earlier and become familiar with how these cars work, before you go to the trouble of rewiring the car. (Mostly because some of the wires will be difficult at best to reach under the dash)


I suspect you will find wires that are melted to each other in the bundle. And melted plastic connectors that are not allowing terminals to make good contact.