(... Lots of good math and analysis...)
I still believe the actual “issue” is the way the back of the block is machined, relative to the decks, main bore, cam bores.
And I think it’s always been that way.
Just get another block and start over.
Feeling the same -- If they didn't re-deck it, then displacement and compression would be all over the place from the front cylinders to the back, and it would run like ****. If they re-decked it, but didn't start wondering why there there was over 100 thou of error needing fixed, then they're completely insane or completely clueless. And, even if they did redeck it that way, I still think the mains and the connecting rod journals would bind like hell with so much angular problem in them. It seems very unlikely.
But if it's the other case -- that the back of the block is machined out of square and has been since the factory, then I come to the opposite solution. Shim it back up to perpendicular, and call it all good. If it's jsut the rear flange then the crank and the rest of the engine can plausibly be presumed to be fine which is consistent with the dyno results that show it performing. Once it's shimmed perpendicular, then the clutch and input shaft are back in angular and linear alignment, so I don't need to worry about clutch wear or input shaft bearing problems. So there's no problem. I can live with having a couple pieces of shim stock between the block and the block plate.
