For my friends shop, I converted his Acer 1440G lathe into a 1440E. The vfd converted the single phase 240 vac into 3 phase 240 vac and speed control. After much tought I used the old fwd/rev relays to signal the vfd for the desired spin. I deleted the coolant pump motor from the circuit ( operator did not want it ) to make power supply simple. I believe I can do this with any lathe on the market. I have used vfds to convert 120 vac single phase into 240 vac 3 phase. You have to derate the power, but still have power to do the job. If you need help give me a shout.
All the Best
Francis