I would replace the HEI ignition module. It sounds like the same over-heating issue that I have seen many times. also, with the new module is a small capsule of heat sink grease. USE IT. if not, keep many in your glove box because they are easily murdered by heat.

The problems we face today can not be addressed at the same level of intelligence we were at when we created them - Albert Einstein Or with the same level of $ - Me