After finally tracking down the correct mounting location for the tach wire to pass through (thanks VA72C10) on the firewall. According to his build thread (
here) [with pics
here], the correct location is between the wiring distribution block and e-brake holes.
A quick call to lolife99 and a few weeks later, I was free and he came down with a uni-bit. If you've never used one of these and need to drill a large hole fast, this is the bit for you. It's actually a "step bit" containing several different diameters within the bit, which "step" up while continue drilling. The tach wire needed to be drilled to just at .75" or 3/4" diameter to accomodate for the rubber snubber on the wire. Here's a shot of the uni-bit with an extension and of the gradual drilling process.
The end result will look like this, although it is roughed in at the moment. A little clean up under the hood and we'll be good.
