Owner says its a 4 cylinder gas...which to me is a red flag. IIRC 600 series were 6 cylinders.
He had a poor piccy on his cell phone and it looked just like the 300/311 photo I "borrowed". NO front headlights, just a rounded front end with missing side curtains I'm told. The grille insert is missing and its been repainted, so who knows?? I'll try to get more info from him. My best guess is that is a 411.