Gear pitch is not important as long as both gears are the same.
The spreadsheet has two RATIOS since most mounts have two stages of reductions.
If your mount only has one gear reduction stage, then just enter 1 in the other.
If your mount has 13 teeth to 217 teeth, and nothing else, then use GR1 = 1,
and GR2 = 217/13 = 16.692.
This reduction is not enough even with a 400 step motor (0.9 deg), and 1/32 microsteps.
So you'd better use a geared motor, and enter that ratio in GR1.
For example with a 50:1 gearbox:
200, 32, 50, 16.692 = 14,837.333
If your goal is visual observing only, then less reduction may work.