Fast forward to this morning when I took the spring plate covers off for re-indexing the torsion bars. I've noticed a decent amount of butt sag on my Bus, verified by the position of my spring plates between the stops compared to similar vintage Buses all parked on level ground. I hit a stop work condition because my bushings are shot (again) and I need to source replacements .. because I wasn't anticipating needing to replace them again. Interestingly, the passenger-side torsion bar had walked outward and was rubbing a bit on the inside of the spring plate cover, so I knocked it back in with the mini-BFH to keep things in position for now.
Driver's side spring plate cover & bushing:

Passenger side, note the shiny spot where metal was rubbing on metal:

Passenger side torsion bar protrusion and shinyness:

Has anyone recently bought new bushings and can report on bushing hardness/quality? I'd like to not have to do this again in another eight years.