So... to continue the saga... I tracked down an appropriate size socket and then tried the leverage thing with my length of conduit of the end of the wrench-handle. I cranked it maybe one more full turn, then whacked it straight in towards the axle (not really that hard even) with a regular hammer. It only took a few hits of the hammer and I heard a glorious pop. The cummulative WD-40 and PB-Blaster plus tension overnight probably helped some in the end.

After I heard that POP! I did a few victory laps around the car, "chariots of fire" theme playing in the background. I must have looked a little strange running in slow motion out there on the street. OK... actually the running part was all in my head!

Anyway, I did find that some previous doofer (PD) had not put in the woodruf key in the slot. I guess I'm lucky the drum was not stuck on there even worse. My next question is where I can find a replacement key of the appropriate size? Seems like it could be kind of an obscure part? Any measurment info on that out there in the group knowledge-base?

Thanks to all in the previous post-thread for the words of encouragement and advice. I needed 'em.