Generator Output at different frequencies
For the generator to deliver 50 Hz, it would need to operate at 5/6ths or 83.3% of the original speed. To deliver the same power, the torque would need to increase by 20%. The prime mover may or may not be capable of that. In addition, the generator excitation would need to be increased to supply the same voltage at a slower speed. The generator may or may not be able to tolerate that.

It is also important to be aware of the difference between real power (kW) and apparent power (kVA). If the kVA is constant but the kW is reduced, the prime mover would not require more torque at the lower frequency. The kW/kVA (power factor) also has an effect of the required excitation.