That may not be a stepper motor, but rather a reluctance motor. if it is a stepper, now that you removed the rotor from it the magnetic field strength may be about half of what it was. not a good option anyway as its only rated for 2 newton meters of torque.
What's wrong with the LG direct drive motor? can you install a 2 or 3:1 gear or chain drive between the motor and turbine?