Faria tachometer

[72 K20]

Hi
My father in law gave me an older Faria tachometer the other day and I thought I would put it in my truck for the hell of it.

I took the back off and it says to wire the tach into the wire going from the ignition switch to the coil.
In essence, wire the tach between the switch and hot wire of the coil............ I have an HEI in this truck,,,,,,,,, think it will work ?
I would hate to mess up this nice old tach.


Thanks for any and all help or input on this !!!

Tom