[304065]

Call North Hollywood or Palo Alto, they can give you current pricing.

You are right, it doesn't work with a stock tach-- MSD boxes output a 20% duty cycle 12V square wave. VDO tachs take an 11 Volt square wave with a 63% duty cycle-- a 50% duty cycle for a 912.

While you are at it they can rescreen the face or make whatever improvements you require.

I had a tach converted to 10,000 RPM sweep and MSD, it was about $250 if I recall but that was last summer.

The "tach adapter" is basically an induction coil that charges when the points are closed and when they open dumps a couple hundred volts into the tach with plenty of ringing, noise and EMF. Sucks a lot of power and heat, inelegant.