Can one be the master? And is sync fixed interval? Do you have an internal clock with greater resolution than 60Hz?
Making assumption both are true, I'd set one as master to transmit at least 4X the desired sync interval - 240Hz in this case. Each transmission would be the position within the cycle - at 4x that could be 0,25,50,75 or as simple as 0,1,2,3 or even in microsecs if you wanted.
The key is that when the slave device receives a packet it knows where the master is in the clock cycle. Then no matter what message it receives you can sync the slave. Once sync'd, then use the receive message to check for drift.
Don't count on any wireless link to be 100% reliable, so sending single message saying measure now isn't going to work.
Hope you find the thoughts useful. Have fun!
Neil