pertronix coil

I just replaced the compufire ignition module in my ghia. It just
quit in the middle of a 4hr drive. I thought I burned it out by
using the Pertronix flame thrower coil with it, but the Compufire
ignition unit claims to be compatible with high-output coils. I'm
running now with the 20 yr old bosch blue coil until I can be sure
the Pertronix is safe.
How/why does a hot coil fry the electronic ignition units, and how
can it be prevented?
Thanks,
Kevin