My frame ground is from the battery + to the coil bracket on those little wings that hold the coil bracket. The red wires from the battery go right to the coil bracket which is immediately grounded to the frame there. I'm not sure how my engine is grounded, but it is, the early bikes had a wire from the prop stand studs to the engine plate, but I didn't put it back on, but I have good grounding throughout the bike, but I did make a bunch of places that were paint/powder coat free. No extra wires from the original harness. Just lucky I guess.
I'm still looking for that threaded connector for the spring assembly if anyone has one laying about.
Dave
69S