Yup, I should have posted that as well, good catch on the rotor, and as stated above, another very common problem with the large cap HEI's. So common, I tend to forget there are others out there that haven't heard of it yet.
I'd suggest the Wells rotors only, A-Z has them for a reasonable price. Wells stuff is actually OEM GM in different packaging, and is of exellent quality.
Another failure issue is the carbon post/rotor. Might make sure the carbon post is not damaged, and isn't broken off, is installed correctly, and protrudes past the end of its guide on the rotor side of the cap. If the post is installed above the insulator under the coil, there will be a gap between it and the bar on the rotor, and that will cause severe overloading of the coil/module, failure to follow.
Proper sequence is...post (spring end up), insulator, coil.
HEI's are really finicky on little stuff like this, and will find any opportunity to fail/kill electrical parts they possibly can.