I went ahead and ordered an M.Zuiko ED 75-300mm F 4.8-6.7 II lens while it's still on sale for $399.99 (US). It is on backorder and is expected to ship in mid-April. While I was at it I ordered the LH-61E lens hood to go with it, for $24.99.
The Logo on that lens cap is seriously ugly in my eyes. At my age, I remember that Logo. In spite of my curiosity about all things Olympus, I can't help but wonder if that Logo kept me in the Canon FT-QL camp throughout the 1960s and early 1970s.