Drum brake weights interfering with cragar ss wheels

You hit the nail on the head.

What I can't understand is how they can cast a drum and it be so much out of Balance that it requires 2 - 2" long 3/8" thick weights
Exactly. I have a little vibration but I couldn't tell you if it's the tires and wheels I installed (they were balanced already but I didn't check them) or something else. Whatever it is, it's not bad enough to worry about.