2 axis to 3 axis conversion issues

I'm adding Z axis control to my bridgport. Its setup with an Anilam
Crusader M control, controlling X and Y though Z is currently manual
with a glass scale. So I aquired an older Z Quill drive built by Elrod
Machine (the newer models had an integrated scale for feedback but
mines an older one without any encoders in it.)

So heres my challenge... I need to mount a rotary encoder on the Z
axis quill (I'll mount it directly on the upper side of the ball screw
which is a 5 TPI, turns per inch, unit). Since the control doesn't
have any way to configure the encoder inputs (like the number of
pulses per inch), the rotary encoder needs to provide the same pulses
per inch as the glass scales have. The glass scale on it now is an
Anilam D-10.

Since I haven't been able to find any information on the D-10 glass
scale, I'm hoping that someone out there might know what the
resolution of the D-10 series scales are as well as its electrical
specs (I'm don't know too much about analog signals). With that info,
I'll be able to select the proper rotary encoder.

Any help is greatly appreciated.
Michael