I've never heard of one being converted to run 240v single phase. You could make the control side run on an isolated 240v supply with a 115v step-down transformer like the old yellow builder's cube. There's still the problem of running the spindle though.
You could buy a small single phase to three phase inverter and set it's output to 50Hz and then change the input to the transformer for the servos.
Getting tapes, drives or even the disk emulators for BX controls is nigh on impossible unless old units surface on scrappers.
Edited to ask: Is this a KMB1 (swan neck casting, fixed ram and inverter spindle motor) or a KMB1-M / X (sliding ram, varibelt spindle drive)?
Got a serial number?