I had noticed some scoring on the cam lobes too, more on one than the others. Likely #6. The blackened #6 cylinder wall tells me that there was a good deal of blow by. I wonder if piston slap may have been the clanking you've been hearing.The block is ready to go to the machine shop for cleaning and to see what can be done with #6.
Here's what #6 looks like from the bottom. Ugly.
View attachment 2606971
Here's 1 thru 4 (picture taken from the bottom). Not bad.
View attachment 2606972
Here's 5 thru 8 from the bottom. That's #6 second from the right.
View attachment 2606973
I should mention that every one of the bearings... rods and mains... all show wear and some scratching. It's obvious that some tiny pieces of nasty shiot was circulating around in the oil. The worn metal on #6 piston and the scrapings from the cylinder walls of #6 had to go someplace. I guess getting trapped under the oil delivery holes in the bearings was as good a place as any.