Can I use a 50Hz tape recorder on a 60Hz electrical system?
It should work fine ( 60Hz running on 50 sometimes doesn't work) but if the motors are synchronous to the power grid it will run fast. Wether playback at 1.2x normal speed is a problem or not is up to you. If you are recording and playing from the same machine then it won't matter.

Grid-synchronous timing was very common decades ago (analog tv for example) - the AC frequency was stable and reliable. When devices moved to DC motors and digital control they stopped caring about the mains frequency and just generated their own timing signals.