All of the mounting hardware for the two different headlights are identical...same part numbers. That means it will bolt up, if you don't have a clearance issue then yes you can. The '14 headlight appears to be smaller than the '13 headlight so it doesn't look like you'd have clearance issues either.
Is it possible to swap out the headlight on the 2013 highball for one off the 2014?
Well kind of.
It will bolt up yes.
But the 13 headlight has 2 H8 bulbs.
The 14 headlight has a single H4 main bulb & a small running bulb.
The wiring for the running light should be in the harness. But you will need a converstion harness to go from 2 H8 wiring to Single H4.
I like the old school look and put and older Vegas headlight on by bike.
But I do have the conversion harness I bought & never used forsale because I thought I was gonna go that route.
I have a Bullet to judge headlight conversion harness. Plug & play Dual h11/H8 to single H4. $27 shipped.
I never used this.
The factory harness has a wire labeled frt ind that is for the small light in the bottom of the Judge headlight.