Everything you found was to be expected Dave conforming to colour code standard. Even the solid green wire tail to indicators each side being same since lamps are generic and it's the main loom wires feeding them that differ.
I get the impression you are close to giving up, however you need to be a little more adventurous I suspect. Cutting a few of the thinner cable ties which are easily replaced, will allow a closer look and I would expect to be looking in the area just aft of wheel upright. I can see several taped sub looms there. You may have to cut away tape carefully with a Stanley knife to reveal cable colours within. Remember you have found the correct wire at the dash end so where else would it go
Note also that your wishbone conversion may have required some non standard loom securing.
That bomb tail (bunched group of wires sharing a common feed) needs attending to. Try soldering them all together if possible or at the very least re-crimp. Clearly the one you found was to share a common ground but they are used extensively on wiring looms so the insulation needs to be in place, as often live WRT ground.
