After dyno sheet showed lean condition during 2 pulls (A/F in 15-16 range), I decided to borescope at Brent's suggestions...which then led to pulling heads off. I'll deal with shop that ran dyno'ed with lean condition (yes, inexcusable).
After removing heads, I saw odd, bad, and truly ugly things.
. I've posted a few photos and would appreciate thoughts/comments from experienced folks on the following:
The Odd:
First thing I noticed was sticky dark oil residue on tops of all pistons and back side of all intake valve. Also could see on tops of piston oil pattern where it bulk oil was migrating across top of piston much like water on a windshield. That led to investigation of PCV tubes and fitting (stock CJ resto stuff) where I found evidence of oil. Oil baffles had been from the stock CJ cast valve covers to clear the rockers. My understanding if IF motor was inhaling large volume of oil, that would greatly increase chance of detonation.
The Bad:
Signs of detonation. I'm no expert of forensics but it appears the detonation was extensive enough to escape the past the head gaskets and leave combustion residue including the sticky dark oil residue on the block-to-head mating surface beyond the metal ring of the head gasket.
The Truly Ugly:
Two fairly deep scratches in #8 from two small pieces of debris that embedded into side of piston just above top ring. I don't know if the debris could have been caused by detonation or lean condition. (Side Note: When new valve guides were installed, it broke/chipped bits of the head's guide boss as the guide was pressed in. I've always been leary a small chunk of the guide boss could further crack off and get inhaled. But I would have expected to see a bigger piece of loose guide boss than the very small pieces of debris that caused scratch.)
Pulled the number 8 rod/piston and bearing and crank look fine.
At first it appeared I could simply clean up the oily residue and address the PCV issue and retry on dyno (obviously at different shop) using higher octane, richer carb setting, etc. But upon discovery of the scratches, looks like ill need bore job and bigger pistons.
I don't know if the lean condition and detonation caused the debris that led to scratches...of if they're separate and unrelated.
So I suspect I'll be boring as needed and new pistons. Dadgum it.