"Starter relay wiring harness" replacement options?

[THE-HOG]

I'm looking at replacing all the wires between the battery, starter relay, starter and bulkhead, basically all the wires on the driver side wheel well. I really don't want to do a full rewire, and I don't even know what to search to find these wires and connectors, so I figured I could ask if you guys have any ideas on where to find replacements.

 

[THE-HOG]

If you really want to rip your hair out I'll tell you that this black wire supposed to be a neutral start switch (on a manual truck) follows the frame all the way back and goes into a tail light.