Some follow-up my Pertronix Ignitor III project. As I posted earlier the first unit worked fine for awhile and then started acting like it was temperature sensitive. I sent that one back and installed a new one. That one worked fine for a few weeks and then started misfiring at low RPM. Sent that one back and they said it had a bad power transistor. Been using my backup unit for a few weeks and it seems to be fine. All of them were replaced under warranty and Pertronix has been very helpful. They insist that heat is not a problem for the Ignitor III.