I take it you mean you bought the lathe with a 3ph motor that had been supplied directly from a 3ph mains supply.
To run it off 240 1ph it will need an inverter, and you can buy these with a variable-frequency speed control. (To enhance the belt drive and back-gear, not replace them!)
I fitted my ML7 with a complete motor + integrated inverter/ controller, from Newton-Tesla who sell those complete sets; but the electronics alone are available. I’m not sure if from NT but it’s worth asking.