I ran a line back to the rear running light. It's wired under the tank.
This is probably not an ideal place for everyone. But, I didn't feel like uninstalling my fairing wiring the light up and then reinstalling everything.
This is a 1 7/8" tach from Drag Specialties. (maybe specialists)
It's very nice. The chrome and black face match the OEM suzuki speedometer very nicely. The needle spools up with no deflection and it's operation is very smooth.
It's pulling juice from the horn wire, as suggested by others but I went with a simple ground to the frame. I installed wire-ends to the ground wire and bolted and mounted it onto and extisting bolt.
For the coil connection, I didn't have enough space so I cut the white Suzuki wire and extended it just a bit and mounted both the Suzuki white wire and the tach's coil wire to a new female blade connecter and slid the new assembly on the negative coil blade.
As with all of my wiring, it's a little ugly at the moment. When I have more time and I'm not distracted, I'll go back and clean them up and put weather-proof slides over the connections.