Even with a cut harness, the correct wires should be somewhere around the seat. Splicing into those would be a lot easier than running wire from the headlight to the tail.
This. And then turn on the turn signals and probe the ends of the cut wires until you find the one with the voltage turning on and off. Take note of the markings on the wire and then repeat for the other turnsignal. signal.
That's what I did. found the wires! Sweeet.
Can I use any kind/gauge wire?
I'd run six or eight gauge to be sure.
(Actually 18 or 20 should be fine. Use what is there now)

750MCM should be plenty.
