It could be that someone was in the engine for some reason and didn't properly torque the cams down. That's the only reason I can think of for the loose bolts, cracked boss/cam bridge, and resulting ejected rockers.
The good news is that even with all the miles and malfunction of this engine, the cylinder walls look really good and there is no wear ridge at the top. We are still probably going to get it bored .020 over.
There is a dual "flange" behind the center freeze plug on both sides. It makes tilting the freeze plug to get it out a major pain in the ***. The plug bottoms out against the flange and won't tilt. I had to drill a hole in both plugs in order to weaken them so they would bend enough to get them to tilt so I could grab them with my channel locks and yank them out.
I have all the main bolts (and side bolts) out, I just need to figure out how to get the main caps off. They are in there TIGHT. I'll then be able to remove the crank and inspect the main bearings. After that, I have 2 freeze plugs on the back and some dowels to remove from the block and it's off to the machine shop.
I guess it might help if I remembered to back off the jack screws before attempting to remove the main caps. DOH! Oh well, the crank is out. I took some photos but they turned out blurry. The camera keeps wanting to focus through the cylinder and on the floor at stuff there. I'll have to try again and post pics of the main bearings and crank. Once again it looks like the crank took no damage. All 5 main bearings are trashed, with them getting progressively worse from front to rear. This points to oil starvation once again.