If you're interested Tim, I've got an Ultragauge thingy that reads out RPMs, MPH, coolant temp, etc. It's a little GPS shaped thing that plugs into the OBDII port. I'm sure it would make the needle calibration a lot easier.
Mine: 2006 Mazda3 s GT Hatch: 115k, Gray, Manual
Gone: 2002 SVT, #1654
Hers: 2012 Focus Ti Sedan: 55k, SGM, Manual