1972 Dodge Colt

I took the head I ran last year to the machine shop today.
Bronze wall guides, narrow stem valves, performance valve job and a .050 cut.

We talked about the other head, he wanted it to pressure test.
But if it's bad at this point, what would it help, other than to know what was wrong.
I looked the copper gasket real well, I could see no issues.
Thinking about water paths into oil from the gasket, there is only the rocker shaft oil passage at the rear.
That is real far from a water path from a head gasket.
It seems much more logical to me that water would mix somewhere in head casting, not the gasket.
I welcome any discussion on what might have happened.