In post 1 you mention you have a msd 6a. Is the thin red wire for the ignition wired to a switched 12volt source and not through the ballast resistor?
I had a customer bring a vehicle to me with a hot soak no start issue that had been going on for a couple years. Car would start fine cold, he would drive the car somewhere and when he would come back out it wouldn't start. He would leave the car to completely cool down and when he came back it would start right up.
He drove the car to my shop about 30 miles and when he got here he shut it off. Sure enough it wouldn't start.
Long story short it was the ignition supply to the msd. It was wired to the resistor wire from the ignition switch. When the engine was cold the cranking draw on the electral system was low enough that the ignition supply was just above the threshold needed for the msd box to work. When the engine was warmed up or heat soaked the demand on the electrical system when cranking the engine was higher putting the voltage at the ignition wire just below what the msd box needed to work properly. I ran a test wire from a 12 volt source and it started right up. He was so happy as he had been fighting it for about 2 years and was ready to sell the car (his high school car). Years later he is still happily driving the car.
