Didn’t realize that was an ad, clickable link. Doesn’t understand how the catalytic converter went after the head gasket blew? Haha. If you vehicle runs rich it’ll eventually take out your catalytic converter hence why you want to make sure your oxygen sensor are working, if it’s throwing a code and you ignore it and just drive it, usually the vehicle just defaults to running on the rich side. The fact that it has a misfire, no AC, shakes at highway speed and looks like it’s sat for five years. I wouldn’t touch it with a ten foot pole.
Oh I see he changed the catalytic converter with the new “used” engine. Either it was bad to start with, clogged, or maybe its got an oxygen sensor going. I still wouldn’t even consider looking at it unless I really had my heart set on a VAN.