Thanks for all the suggestions. Fortunately the first thing I tried happened to work. I jacked the car up again and sprayed some PB on it and let it sit for awhile. I happened to have a new pair of vise grips with some good teeth on them. Clamped it on the edge as best I could and it finally broke loose. I couldn't believe how much strength it took.
Anyhow I got it off ok. Oil and filter changed! Installed the original drain plug.
Yesterday where I started to tackle this I was kind of tired from already changing out the spark plugs and tubes. So, I think a fresh start this morning helped.
Here's what the plug looks like.
