Interesting to see what you have there; I just got done pulling the rear drums off our 1955.1. We're comparing Huck vs. Bendix brakes, and we have SRW not duallies, but I thought I'd at least reply and see if any of the Bendix method worked for you. On the Bendix, you don't need to remove the hub, and there are two large slotted screws that hold the drum on. Those have to be removed first, then you can bang the drum around. You may or may not have these; I am unfamiliar with the Huck brakes.
Our brakes spun no problem as well, but when you tried to pull them off, they did not want to come out. The drums had been so worn that there was a lip on them that was catching on the shoes when we tried to pull them off. Had to drain the brake fluid to release tension, pulled the drum off just enough to get a bar in there and compress the shoes, then managed to get it off by having one person pull on the drum while another beat on it with a metal hammer from the side. Each hit let it slide just a bit more.
All of this may be completely unhelpful, but I wanted to at least chime in with my experience since you don't have any other replies yet.
