Someone wanna help find the cause of death?

The 5/6 pair seems to always be the first to feel an oil starvation issue.
I'm sure your block is fine, and the crank will probably be OK after a clean up cut.
Look carefully at the pump.
Original problem could have been something as remote as a pushrod bending and allowing the lifter to jump out of its bore.
These engines feed the lower end oil through the lifter galleries