could you please clarify your question?
this doesnt make that much sense to me..
find me a single instance where there was a named head coach of an ARCH rival to coach at that other school.....
It is simle, show me here in the south where one of the Schools..i.e. hired a former player/alum of their ARCH rival to be their head coach. Coordinator's do not count.
I.E. an Alabama hiring as permanent head coach a Auburn ex-player as head coach or a Uga hiring a GT player/alum as head coach or a S.C. hiring a former Clemson player/alum as head coach.
Now it doesn't count to just hire a former player of one of your rivals, just ARCH rival. Dooley from Auburn doesnt count because Uga's ARCH rival is GT.
To my knowledge it has never occured.