Yes, thanks to Mr. Healy for those clarifications!
After reading that post I went over to the shop and took some photos. I have my bike's original clutch center (57-1734) as well as the updated part (57-3929) from MAPCycle. In each photo there are two thrust washers for both hubs - one new and one used. The two photos show the two sides of all the thrust washers.
The updated 57-3929 center has 11,000 miles on it. Both it and the 57-3931 bi-metal thrust washer show a good deal of wear.
The original 57-1734 center and original 57-1735 bi-metalic thrust washer have 65,000 miles on them. Note that the original thrust washer is the tab type.
Given how apparently prone the inside diameters of these thrust washers are to wear, I don't understand why they would be made with a bevel there. Undoubtedly there is some explanation beyond the ken of an amateur such as myself.
Anyway, looking at the relative wear of the original and updated parts, and since I have a brand new copper-plated 57-1735 thrust washer on hand, I think I'm going to revert to the original 57-1734 center if it is compatible with everything else.