oh i thought you want a TV...sorry 4 the mistake. but as rtv says 75hz are also fine. as long as it is a multiple of 25! another option is reclock, which could speedup the video material to watch it at 60hz..
You certainly would not want to speed up movies / increase voices by 20%, would you?
With ReClock you can resample the audio pitch to match the original ...but of course no one should run movies at 20% faster playback rate. And its also impossible for live tv, as no one has invented any time machine(s) yet.