Both motor-generator units and electronic frequency converters are
available, but neither is inexpensive.  The cheapest solution would
be to increase the motor pulley size by a factor of 6/5.  The motor
will run a little hotter on 50 Hz if it was designed for 60 Hz so
you need to make sure you don't overload and overheat it.

Best regards,
Spencer Chase
Garberville, Calif.
http://www.spencerserolls.com/