Step resolution question, dividing head

I'm working on setting up my Hardinge dividing head for a 4th axis.
I think I've figured out a ratio that gives me even steps, at least for
full degree moves, and wanted a double check that I did this right.
Dividing head has 4:1 ratio, so 90 degrees per full turn of the handle.
With 18,000 microstep resolution I get 200 steps/degree and with a 2:1
reduction between motor and dividing head, 400 total microsteps/degree,
or .0025 deg/microstep.
Does this look OK? I need to get the ratio settled so I can pick exact
timing belt pulleys, and finish designing the mounting plate.

Thanks,

Jon