RK05 spindle pulleys - trade 50Hz vs 60Hz?

[GerardCJAT via cctech]

Why don't you simply power it through an inverter that will output 60 Hz, 
eventually even "down to" 120 V , true sine wave, of course ??? They are not 
that expensive by now. 
And be carefull : motor designed for 60 Hz, running "under" 50 Hz, OR THE 
OPPOSITE, I do not recall  !!!, display a significant reduced life time.
I have to check which is which, but I know this is a question of saturated 
magnetic field. Better check first.