[1] I would get a coil that has the correct primary resistance....& an E core coil. Two examples are the MSD #8207 or Summit # SUM-850500, $75 & $42 respectively from Summit.
[2] 1" spark. Sounds like that coil has a high turns ratio, which is trading voltage for current. You want a coil with high current, because it is the heat [ current ] in the spark that causes ignition.
[3] Overheating GM HEI module. The modules are internally current regulated to 5.5 amps, so they do not overheat. The only one that I am aware of that is higher is the MSD# 83647, 7.5 amps.
[4] Use 0.060" plug gaps.