spindle speed pick-up using the bull gear

Hello folks,

Wondering if anyone has incorporated a hall effect sensor in their Bridgeport gear head to pick up real-time spindle RPM.

My plan is to drill and tap a hole to pick-up the bull gear teeth with a hall effect sensor, then wire the sensor into my encoder_4 inputs on a  mesa 7i77.
Is this is viable? If it is what I am looking for is measurements and locations on where to drill/tap the hole for the hall effect sensor, also what sensor do people use for this job? I currently have a ZF GS100502 gear tooth speed sensor good to 15khz.

I have the following hardware:
Bridgeport V2XT {1996) donor mill using the legacy servo motors and drives.
Mesa 7i92M and 7i77D
cheap amazon VFD.


Please advise.
John VanAtta