Diston, you're right about the chain slop although it's actually severe enough to chew into the bearing carrier -.
You can see how slack it is here -
I was kind of anticipating a worn chain and/or sprockets. But that's not the immediate problem.
What I can't understand is why the camshaft tip can be turned independent of its sprocket. And I mean turned completely, not just a little bit. Like the woodruff key is sheared.
It still doesn't explain why when I turn the crankshaft, the camshaft lobes turn and engage the valve lifters. Something's not adding up. Replacing the timing chain and gears, tensioner, etc., would be pretty straight forward but I'm sensing a bigger problem. I was hoping to avoid an engine tear down for a while. Any ideas?