GOT IT!!! Mission ACCOMPLISHED!!!
I drilled and tapped the key to #8-32. I found an old long stud and a nut and used the slide hammer to back the key out. I also used a piece of heavy pipe and a hammer to drive the pulley about 1/16" further on, so I knew it wasn't rust welded before I attempted pulling it.
Then, I used a 5/16-18 x 3/4 Gr. 5 bolt screwed into the non-keyed setscrew hole. I looped some heavy wire around that and pulled it with the slide hammer. Sounds a lot simpler than it really was. I broke a dozen pieces of wire, used 1/4 can of PB Blaster, used a lot of Mapp gas to heat her up, and didn't drink ANY beer (Saturday morning).
It's off and back on for a while. I'm very grateful for all the suggestions, warnings, and encouragement.
I didn't screw it up, and I didn't give up either. The key was heating the collar.
