The 340 is out....again.....

I think you can cross the pickup off your list as being the issue; at least its position on the pan from what can be seen on the pan bottom.

How did the main and rod bearings look? This is fairly important to know to try to figure out the probable cause. I apologize if you answered this before; I have just missed it if you did.

Edit: And actually, the answer to that question has been right before my eyes all along. In the 3rd pix you show, there is a pair of rod bearings lying in front of the 2nd piston from the right. It is badly worn, down to the copper....ow! This may have actually been the knock that you heard. That same pix also shows full groove mains; they are showing the start of some wear. Both look to be due to the lack of oil.

Were all of the cam bearings damaged the same?