Tach Sensor

I could use a little help with a tach sensor.

I have a Red Lion Controls Cub5 Counter/Rate Indicator that I would like to
use for a spindle tach on my Dyna-Myte mill
http://www.redlion-controls.com/products/doc/01012.pdf

The sensor trigger levels are
Vih: 4.2V min
Vil: .5V Max
V Max: 28VDC

Current sinking: internal 40KOhms typical pulled up to 5V

Ok, I assume the Vih is the min voltage pulse required to trigger the
counter. Red Lion sells a magnetic pickup as an option for the sensor. Could
I simply mount 2 magnets on the spindle pulley 180 degrees apart (for
balance) and a coil of wire wrapped around a steel shank, placed close to
the magnets as a pickup, and if so, will that generate somewhat close to the
voltage required to trigger this thing? Will some sort of pulse shaping be
necessary to clean up the pulses?

If I will need an amp or pulse shaper for the above, should I just use a
photo reflective or interruptor type sensor to put out a 5V pulse to the
counter? Is there one, that anyone knows about, that requires no external
circuitry, just Vin and ground and outputs the required pulses? Photo
reflective would be prefered. Price is no object as long as it's cheap.

Thanks from the electronically challenged.

Bill