Don’t think I’ve ever seen an “H” with a wiring harness that was truly original, unmolested, and intact but this is what I believe should be reasonably close to original for the starting and lighting option.
Start with the correct BCI Group 1 battery which must be oriented with the negative (hot) terminal on the left side. The armored negative cable will be routed upward from the battery and then threaded rearward over the two fuel tank bottom supports, and between the fuel tank and the hood. Just prior to reaching the starter, that cable emerges from under the hood and then attaches to the starter terminal. (see the picture)
The positive ground strap is probably sandwiched under one of the 7/16” cap screws that fasten the bottom water pipe to the head of the engine as no fasteners are listed in any parts list for the termination of that ground strap, so it must share an existing fastener.
From the generator/cutout relay area, the harness containing the field wire (#4) and the wire (#5) from the BAT terminal of the cutout relay is routed rearward and is attached by loop clamps (A1225R or A2610R) that are sandwiched to the underside of each of the two fuel tank mounting bracket clamps under the existing clamping nuts. Those two wires then attach to the light switch and the ammeter respectively. Wires #6 and #7 are short and likely go directly between termination points without additional support or attachment anywhere.
The lighting harness (containing wires #1, #2, & #3) apparently uses six of those loop clamps. Starting at the light switch, that harness drops straight down to the main case, goes under the magneto and then toward the steering support shaft, and then splits into two branches, one with a wire for #2 & #3 for the two side lamps, and then continues as wire #1 for the rear lamp. The branch for wires #2 & #3 chases up along side the steering support shaft and then splits into two individual wires that are threaded into holes in the bottom of the lamp support tube and then outward to terminate at each of the side lamps. Wire #1 is curved back toward the accelerator pedal, is threaded under the clutch operating rod, then under the right footrest of the platform, and back toward the rear lamp. There are six of those loop clamps that are assigned to the lighting harness. I’m fairly certain that the wire for the rear lamp uses three; one at the rear lamp mounting bracket, and another sharing the bolt supporting the platform where it is attached to the right side of the main case, and a third at one of the first reduction gear cover bolts. I don’t know where the other three loop clips are supposed to go; probably under the crankcase cover bolts and/or the governor housing bolts.
All this is only an educated guess. If someone knows the exact arrangement from the factory, please let us know.