Hi, Modiol,
You have an 'outside oiler' line, a common fix for a plugged internal oilway to the rocker arms.
That line and fittings was sold as a kit, by most parts houses. The line goes around the back of the engine and is connected to the oil gallery on the lower left side of the engine, by removing one of the 1/8"NPT plugs.
If you will be rebuilding the engine, or at least having it apart and cleaning it up, clean out the original oilway, and you'll not need the outside oil line. There was, originally, a pipe plug in the head where that oiler is now fitted.
cheers
Carla