You would be correct. I was lazy and kept reaching in thru the window to crank it over. I'll spot check a few of the easy ones tonight with proping the TB open.
I'm also thinking of doing a leakdown to see if one of the cyls leaks into the water jacket. Machine shop said he's only ever seen warped heads and burnt exhaust valves. And even a warped head is pretty rare. But the PO's had neglected the deathcool and everything was pretty clogged. So overheating probably happened at some point.