Hi Splais,

>>one Pe sells that incorporates a ground

If the switch has a wire to ground, then it has to be grounding something that's coming from somewhere. Did the engine come with a wiring diagram? If it did, can you describe it, or scan it and post if you have a scanner?

I think your best idea was to write Pe and ask him. I've heard he's really helpful and he could give you the correct answer in a second.