Gas Lighting Pipe Needs To Be Covered

This Old House

I finally got someone to change the light fixtures in my hallway & office -- look what I found.

 

  

That is the gas lighting pipe, from before this place was electrified.

It sicks out about 3". The previous fixture screwed into a nipple in the pipe. Now, it's just hanging by the wires.

This is what I want to put in it's place -- any suggestions?

 

There aren't any threads on the stem of the replacement fixture.