Hydrolock???




The second pic of the driver's side head shows signs of corrosion on the head surface (in the middle) as if it's had water on that surface for some time. Did the gasket seem flimsy in the center on that head? If it is corrosion and the rest of the head surface is not as corroded (they are usually pretty clean) then you probably had a blown gasket or warped head. If you clean it off and put a long straight edge on the head you can easily see if it's warped in the middle.
Also those two inside exhaust valves are a totally different color (possible water leak) than the two outside valves on that head.

The inside passenger valves have a similar look to them but there's not as much corrosion in the middle but the center of the head looks different than the outside surfaces (like the driver's side).

treblig