Dan,
Have you found any correlation between the clock style date codes on the base and the carb tag from known OEM units?
FWIW, I have a 6Z C with a 5HE tag and the 11-5-63 tooling. I haven't studied these anywhere near the level you have but my best guess is the cluster of dots in each section of the clock denotes the week in the month when it was cast however I have nothing to back up that guess.
Steve