stepper motor speed and torque calculation

The bipolar geared stepper motor I am planning to use has a resistance/ phase of 8.5 ohms per phase, inductance of 2.14mH per phase , normal current per phase is 2 amps, holding torque of motor is 0.8Nm, gearbox ratio is 1:8, holding torque of gearbox is 6.4Nm. The maximum permissible RPM of gearbox shaft is 200 rpm. The input voltage rating of the stepper motor is 24-48 volts. I am planning to use a 24 volts power supply and DRV8825 driver to drive this motor. Can anyone help me on how to calculate the maximum RPM of the stepper motor ? And also usually how long can the motor run at this maximum speed ?

Also, I intend to use this motor for a motorized cord reel application, where I would retract a cable using this motor and a chain mechanism. The total weight of the cable is around 12 kg. Would this torque of 64kgcm (6.4Nm) be sufficient for this application?

Attached datasheet of motor here:

for a gear ratio of 1:8 , with o/p speed limited to 200rpm , the input speed will be 25 rpm.

also , if the motor torque is 0.8Nm(holding) , will it not reduce the torque in the o/p for 1:8 ratio gearbox?

Using the specs in your pics in round numbers you are 15x under power, assuming a 50mm pulley.

Trying to factor in your cheap-oh stepper drive you would be so far under powered i can only take a wild guess of 30 to 50 times to low.

Steppers are used for positional accuracy. This is a bad application to use them in. Look how the torque drops off with speed i used the 200mNm output spec. A DC motor would be a much better choice, it will keep a fairly constant torque over the speed range. But you can probably just use a relay to turn the motor on and off and not use any motor controller.