Bport Tachometer

Has anyone installed a magnetic pickup for digital tachometer on a
Bport Type I J-head?

This type of sensor typically reads a gear or something ferrous w/
teeth. It'd be nice to avoid having the pickup travel up and down in
order to keep alignment with its gear. Maybe the drawbar, somewhere
protected under the cover?

I'm hoping some clever member has already ironed out this
installation.

Thanks in advance.

Jack