Need help finding one particular wire...

If I understand what you did?????

You used the "crank" or "start" wire feeding to the start relay to act as an ignition bypass?

You CAN NOT DO THIS unless you put a series diode in the wire leading to the ignition. That's because the ignition -- when running -- will backfeed to the starter relay

It should not be that difficult to trace down the original wire---don't you still have the factory connector coming off the ign switch, in the steering column?
I didnt do that, both wires the blue and the brown only had 12 volts coming from them in the start or run, depending on the wire, in the diagram I have both of those came from the ignition switch, I dont know about the starter thing, I have had mine hooked up like this since July and I have no problems, this is going to a trigger in the 6al, so I dont see how that would back feed. I start my car every other week in the garage, as we have snow so I am not going to drive it, but I let it warm up to operating temp then shut it down.