Dan,
Great description of the plating process. I also worked in a plating room when I was in High School, but it was silver and gold plating. I also worked a whole summer on the stripping tanks where we removed defective plating with cyanide and acid baths (it was fun joking with girls that I was a professional stripper!).
I agree that the holes in the Dyna shells had to be designed for the plating process, but I think they served two purposes: First to enable easy hanging from the electrodes, and secondly to facilitate drainage of the various dips. I'm sure that anyone who has ever put a chrome shell into a bath overnight to eliminate rust has noticed that the water collects on the inside of the bearing edges. Turning the shell upside down to drain the water only transfers the water to the opposite bearing edge. Having these hole predrilled into the bearing edges probably enabled all the plating and dipping liquids to drain easily.
Just my educated :2Cents:
Mike