I am trying to visualise this. It almost sounds as if there is no valve guide in the head for that valve. Since they are driven in to place with some force and reamed for the valve you might have to pull the head.

First make absolutly sure there is none there. Hard to believe someone would put a head on with a valve guide missing. Yet strange things are periodically found. It would account for that smoking though. No way the guide could drop into the engine either if you think about it. The head of the valve is so much larger. Depending how long this has been the situation I wonder what the valve seat is like.