You can order these with a UK input plug and get your 60Hz 110V power this way:
https://www.kccscientific.com/product/1930/
I have used other solutions too. Often the rotor in the clock is a separate item, available in both 50 and 60 Hz versions, if you are lucky you might find one in a clock on ebay.
In one case for one of my 110V 60 Hz clocks, I disassembled the rotor assembly and Ken Reindel machined a new gear for me (near the output shaft) to alter the ratio to correct it for 50Hz use. He is a master clockmaker:
http://www.kensclockclinic.com