Many broadcast/production quality wireless intercom sets use WFM in some of the following ranges....
518 - 608 MHz in 18 MHz TX and RX bands
614 - 686 MHz in 18 MHz TX and RX bands
902 - 928 MHz
You might want to try those, however your likely to find a plethora of wireless microphones that also live in the 512-763 MHz. I know from personal experience that a single event can have as many as 60-80 wireless microphones which calls from pre-planning when setting up. Good luck, wide band FM is much tougher to scan than MFM or NFM. Some mics are hot but muted and others are always on.
The last list I saw had 492.525, 492.800 for Fantasmic!
I hope that helps.