Yep..the dreaded hydraulic lock...and we all know how this came about.
...and so to recovery. Without going back over the history can you confirm that you never got the engine started...that it jammed under starter motor conditions?
The answer is a qualified yes. Engine was firing weakly but very far from actually running.
Hydro lock occasioned by kjet flooding usually fills all cylinders equally. When the engine is cranked the 1st cylinder to approach Top Dead Centre is the one that is going to lock. In most engines there are usually 2 cylinders at TDC. In this instance No8 rear lh bank] is the offender. Calculate which other cylinder was at TDC and give it extra forensic examination. All other cylinders cannot theoretically be impacted.
I'm not sure how to "calculate," but I'll have a look to see what other cylinder is in the same position.
I am amazed at how clean that engine looks and in particular how little wear there is on the piston skirt. This is either a remarkably low mileage motor that had the oil changed every fortnight or this engine has been apart before. I'll be interested to learn if the piston is std bore.
It did just have a rather strong flush with gasoline.

The car shows 72k miles on the clock. I doubt the engine has been out just based on grime, condition of the bolts, etc. Bolts on oil hoses looked virgin, for example. Admittedly, this isn't a reliable indicator, but it's usually apparent that an engine has seen a wrench. When I got it the fuel delivery system needed work and somebody had messed around with the fuel injection (other than me). As for piston, we'll see soon enough.
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I'd be inclined to go with your suggestion...pull the piston.. rod.. and big end...replace. new gudgeon of course!
I'd pull another piston rod set so that the replacement assembly can be at least weight matched. The original is also a valid balance weight reference.
By this you mean to ensure that the replacement is same weight as the original? I assume that all the rods+pistons are balanced at the beginning. Hmmmm. It's easy enough to balance by grinding weight off. What if I end up with a rod or piston that weighs less than the old parts? Is there a balancing tolerance spec someplace?
You will want to be dead certain you get the right piston /rod combo as there were a couple of production variations over the course of the motor.
Oh my. How do I do that? Are there different part numbers for those variations?
As usual, questions always beget more questions.

Here are a few more:
> What's the size of the external torx (??) socket for the rod bolts? My searching hasn't helped for some reason....
> Also replace big end bearing, I assume?
> Any reason to worry about the other rod (or its bearing) directly adjacent to the bent one?
> Any recommended sources for 6.9 rods and pistons? I'll search by part number when I get it apart, but still... I've got an inquiry active with the Classic Center.
Regardless, the next step is getting the head off and the parts out of the block. Thanks again to all for the help and support on this. And always remember: when reinstalling your fuel distributor remember to put the metering piston back in.

Cheers,