Can Anyone Diagnose This Head?

[ClayW]

Can anyone diagnose what went wrong with this M42?

I installed this M42 in my 1600 a few years ago. I've had intermittent overheating problems. Air kept getting into the coolant system. I changed the water pump, thermostat (twice), all the coolant lines and the radiator (twice). I did not mix water and oil. Was it a leaky head gasket? Something else?







Head Gasket: