I have the same problem! I took my tach out to have MacEwen make the template for the white face gauges. My tach was gone for a while, and I lost the diagram I made. I tried a few things.. but I couldn't figure it out, so I just baught an autometer boost/vacuum gauge and put in the 3 gauge POD on the a pillar. Looks great, everything is whiteface now. Good luck with that wiring, i couldn't figure it out!
~Murt
TTA #750