I think I am going to drill a new hole where yours is and be done with it.
The tach wire on my harness has the grommet attached to the wire still so it obviously went through its own hole. I probably have something else routed in its place.
My 72 FSM shows tach wire in cavity 20 (Next to the purple wire mentioned before). My 73 FSM shows that this is the A/C clutch.
A new hole will work just fine.
Craig