I do remember that oil consumption could be a problem if the PCV screen on the cars got plugged. That was an odd design, there being that metal mesh "filter" located below the PCV valve in the back of the intake, so you clearly couldn't see it.
It SOUNDS like you are describing the last couple of years just before they went roller?
As far as rotating assembly went, the HO got a different one from the LoPo (and had forged pistons up until 92), can't remember if the truck and panther cars got the same one or not? I know the cars had cast pistons. They obviously got different cams and the cars were roller from like 85 or 86 onward and SEFI, while the trucks were batch-fire. LoPo cars didn't get the E7TE's either, IIRC? been a few years though since I was deep in the 5.0L scene, so I may be forgetting or mis-remembering some of this.
I did skim the truck forum TSB's last night after you mentioned it and didn't see anything mentioning rings. Did see some stuff on engine knocking and oil fill procedure. You have piqued my interest, so if you can remember anything else, please let me know.