Hi Lachlan and welcome to Ninjette!!!
To reduce wiring-harness, no need to consult wiring-harness. But at least connect everything and get motor running first. Then start at end with unwanted components to remove:
- headlights
- turn signals
- tail-light
- dash
Trace wiring from those components back to main harness. Go as far as next connector and cut off wiring there. Heatshrink some tubing over end to insulate and that's it. There's really not much weight-savings in trimming harness. I recently made bare-bones race-harness recently for my '08 race-bike and I'm thinking I saved 2-lbs max. I might be able to save additional 1-lb by going to aluminium 26-ga wires and remove all connectors in between with direct wiring between components.