GM HEI conversion questions

Ok got it, I think.
The GM ECU is cheaper, and probably actually easier to get.

And you are saying that if you use a GM ECU that you can put a full 12 volts to the stock coil without it overheating?
If so, this is the part I did not know.
Just trying to be really clear on that point.

Pretty much. My engine doesn't need huge high voltage wires (yet) nor a real hot coil, although I'm thinking that the lack of a ballast and the improvement the GM module gives in switching adds some. I no longer have access to equipment that can truely measure spark ENERGY. Voltage does not tell the "whole story."

There seems to be disagreement on the www about whether you can run a stock coil with one of these. I actually have three systems -- the Cletrac, the Dart, and the "emergency" system I built which I ran on the Dart for over an hour mostly to test reliability of the unknown condition of the coil, and coil heating.

This thing has already come in "pretty damn handy" for test firing two used engines