Thanks!
The FCPReconnect app is exactly what I was looking for!
I exported a batch list of all my subclips, altered the reel name, brought the altered batch list into FCPReconnect, it found the other cam as the right clip to reconnect, I chose to copy by ref and keep relative path then made the ref files.
I imported the batch list back into FCP and reconnected!
A few little issues:
some of the files were created with the .MOV extension in the middle of the filename instead of at the end.
FCP still complains about the media start and end not matching on the clips.
Am I doing something wrong?