[Amar Shah]

If you are using a linear mechanism for lifting, the gear ratio does not tell much. What ultimately determines the speed at which totes can be lifted is the relationship between turns of the motor and distance traveled, and is affected by both any gearing you do and by the radius of a winch spool or pinion gear meshing with the rack, or the thread density of a leadscrew.

Have you considered using more than one CIM motor? There are many COTS gearboxes which support two or three motors.