Thank you for your helpful replies. Now that I have confirmed that Indiana blades were used in the old Shannon Twin Spinner, I have arranged for Mary at Jerry's Tackle and Guns in Highland, Illinois, to make some for me to purchase. She is a nice, knowledgeable lady who makes a twin spin that copies the old Shannon, and will even add the wire leader to the line tie upon request. For people like me who don't feel up to making a spinner from scratch, Mary seems to be a good alternative.
Here's a follow-up question on the subject of rigging the Shannon for fishing. I plan on using a three inch curly-tail grub as a trailer, and assumed I would just thread it on the hook. However, I have also heard about nose hooking the grub on the hook. What does that phrase mean? And which method, threading or nose hooking, do you think is better?