The problem seems to have been solved.
The weekend I posted this, I drained a quart of oil and replaced it with marvel mystery oil. Then I took it for about a 30 mile drive on the highway, transmission in 3 to keep rpm about 2700-3000. Then I parked it until the next day.
Next day, it didn't tick for quite as long when started. I drove it daily, and it seemed to get progressively better.
A week later, after about 150 miles driving with the MMO, I changed to oil to Mobil 1 High-Mileage 10w30. Daily drove it another week. Ticking completely stopped.
Last weekend, I parked it and let it sit for the week. I just started it up, and no ticking at all.
