50/60 hz conversion

CLEARAUDIO got a device available for that conversion. It can convert both 110/220 and frequency tune between 40-100Hz. But quite expensive as sold in Hong Kong for about HK$6500. I think I met the same problem for moving my SYSTEMDEK from Hong Kong to Canada. Dont know whether it works at 110V 60Hz at the right speed or not!

Yes. Pulley replacement is the best way. I had PS Audio and it doesn't work at all. Wasted $1000 on that. I never try SDS so I can't tell you much about it. If the SDS is stable enough then it is okay.

I may be wrong here, but your european spec motor is designed to run at 50 hz. I think it might be possible to damage the motor by forcing it to run at a cycle for which it wasn't designed. I think the safest option is to get a new motor and keep your old in case you ever move back across the pond.