cb400f,
Assuming you will micro step with a value of 10 then the steps per unit will be 20000 with a .00005" resolution.
Size of steppers may not be adequate since you need to see what torque you have at some max velocity you will use.
How are you wiring them, what amp setting and at what voltage is available for the drives. So even though there is
250 oz-in available because of gearing, it may be decreased significantly.
So try them out and if they are too punny then just replace them with bigger ones.
I use 500 oz-in steppers on my small lathe and mill and both have 2:1 reduction.
RICH