Hi @johnstephanou ,
Seems your datasheet is old, please check the newest datasheet:
https://www.nxp.com/docs/en/data-sheet/IMXRT500EC.pdf
Whether you still find the FC6 and FC7 are called out specifically?
In fact, the FC6, FC7 to I2S is no special:

Wish it helps you!
If you still have question about it, please kindly let me know.
Best Regards,
kerry