Bill,
I assume you are talking about the mast bearing. If you are staying with the stock arrangement, the mast bearing needs to be at the depth of the wire prong that extends from beneath the horn button.The button is held by a rubber cushion, so the mast bearing needs to be at a level that the prong touches it, but only when the button is pushed. And yes, the steering shaft is part of the electrical ground path for the horn.
Kent
