Stay with Gearbox or retro fit DC motor etc;

[John S]

2) AC motor controlled by a VFD has to be 3 phase however you change the wiring in the motor from star, 440v to delta, 220v , then feed this motor via a single phase input inverter that takes 240v in and spits 220v out but 3 phase.

Bit of swings and roundabout, DC motor will have more torque but generally not as reliable. AC motor is also variable but not as much torque as the DC unit unless you get physically gear it down with say a two speed belt arangement.