Just been reading a Gibson guitar forum that shows a picture of a J300 artiste circa 1970, I believe this is the guitar in question.
Looks a very interesting guitar and nothing like the J200 or J200 custom or the J300 circa 2003.

There are major differences to a J200 such as the fleur de lyse inlay on headstock, on the bridge either side of the saddle and on the scratch plate.
The Gibson logo on the headstock also states "The Gibson" a sign the instrument was not a standard issue.

Also interesting to read that Gruhn Guitars thinks it may be a one off prototype.

Curious to know how it sounds!