Same exact thing happened to me. I was using HEI with a flame thrower coil. Would start after it cooled down a bit and I limped it home. I have since switched to an E-core coil.
I did the same. You'll want to use an E-Core style coil, as the oil filled type coil tends to overheat.
Speedmaster PCE382.1009 Procomp Electronics Ignition Coils | Summit Racing