engine overheat

What is your question?

My wife recently took our explorer on a 600 mile trip one way. The truck has about 180,000 miles now. Radiator has always had a slow leak but we kept it full. Halfway to her destination she ran it hot and it shut off, after it cooled it would run but missfire. I think it would be a blown head gasket, that engine's heads i've been told are gt40 heads, am i barking up the wrong tree or am i on the right track?