Think I found my problem - rod bearing failure

OUCH!!!
Boy do those pics bring back old memories. A few friends got together years ago (early '70s) and built the 340 I had in my '69 Swinger. One of them was a diesel mechanic and also knew Chevy smallblocks inside out but was unfamiliar with one of the "hidden" oil plugs in smallblock Mopars so it was missed during the build.
I was driving home from work a couple of weeks later when I spun a rod bearing. Both bearing halves split lengthwise and crossed into each other. Boy did that mess up the crank. Ending up getting the throw welded and turned.

Good luck with your rebuild!