Index pulse home

All of the 7I76 encoders inputs are used. To expand on that topic. What if I got 7I85 and use that for the pluse input? Would it possible to just use the z input with out doing closed loop in LinuxCNC

Yes, you could use a 7I85 or 7I75 or a inexpensive parallel port BOB
Bare 5I25 inputs can also be used but you have to be careful and at the minimum
add a 220 Ohm series resistor to prevent overcurrent from negative inputs
damaging the ESD protection diodes on the 5I25 I/O pins

Ok so I was checking some more things on my drives and wiring and the type of output is not compatible. If I interpret the schematic correctly it’s looking for sourcing host side. I will put up the drawing. I think that the 7I85 is my best bet.  The Drive outputs 2  independent Z index one a individual open collector and the other a set of A B Z Emulated encoder output. 
I will need some guidance on how to just pick the index pulse from the encoder input and use it as a homing index.