"my first choice would be that the bearings were assembled too tight (maybe
undersize?)"
One question: Would that be a factor some 60,000-ish miles later?

I noticed something else odd on that #2 piston last night that I couldn't easily imagine up an explanation for. One one side the wrist pin retaining clip looked like it had been hammered outward a little bit. The circlip was slightly bowed outward. The other side was absolutely unremarkable, as were the other pistons. The wrist pin is free and floating in both the con rod and piston, with no discernable looseness on either. I couldn't fathom what would force that wrist pin to the side with any amount of force. Perhaps some sort of bend in the rod? Although I would imagine that as sending the pin back and forth as the G-forces went back and forth as it went up and down.

All in all, I think I won't rev as high once I get it all back together, regardless of the parts I use. 6000 rpm sounds like safer territory. If I want more I'll just get an Honda S2000 engine that pulls to 8900 rpms.

PS - I was wondering about alternative sources for forged pistons. It seems that many Volvo places sell pistons with substantial markups for old Volvos that are actually creatively sourced more comomn (and cheaper) parts intended for other marques. In particular I've seen some forged 92mm pistons (with 22mm wrist pins) for very high performance VW aircooled engines. I was curious what the wrist pin height was on the typical (i.e. stock) B18/20 Volvo piston. How is that measured - from the top of the wrist pin hole to the top of the piston? I measured one of mine last night and got 1.35 inches (+- - I can't recall precisely now). I assume if they are close I could get the block decked to match.
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I'm JohnMc, and I approved this message.