it may not leak I don't know, but what I do know for sure is a crack will open as the temperature rises mate.Right thanks for clearing that up so need to find someone who can pressure test with the head warmed up or in hot water. I am reluctant to do this head mod until a crack is found.
im still mithed by your issues as to what caused them. have the valves been checked yet on the cylinder with low compression ?
all it needs is some fuel pouring in the inlet/exhaust port with the head on its side and see if any fuel leaks through the valve seat into the combustion chamber.