You can easily add HID bulb with slim ballast and it will fit right into existing head lamp. LED head lamp will take a modification to do. Not any wiring, as a HD LED light could plug into the harness most likely, it's that Kawasaki uses a damper to keep head lamp stable and from shaking around thus on the back side of the head lamp there is a molded area where said damper bolts into to keep head lamp secure. I took a gamble and purchased a head lamp with projection lens (not a big fan of using a HID without projection lens) and the lens that came was a universal. It was a universal 7" round that could be used for a Vulcan or say a 67 Camaro or other older like wise vehicle that had/has 7" round head lamps.
I winded up returning the lens as I did not want to get deep into taking apart head lamp by cutting out glass and drilling in the projection lens. I'm waiting for near future for when Kawasaki or a aftermarket Co. comes out with a direct fit especially made for Vulcan set up. Other option could possibly be removing entire chrome head lamp housing and using a HD housing so you can hook up their LED light (which is a very nice head light). Expensive though for a LED light HD charges as well.
So unless you can fabricate a bracket on back on aftermarket LED lens and get it right so the damper connects to it securely, HID's are the next best option.
2011 VN1700 Classic.
Cobra Fi2000 PowrPro Tune
K&N Air Filter
Mustang Sport Touring Seat - Studded
Slipstreamer Stealth Windshield
Kawasaki Engine Cover Trim
Sissy Bar Studded Backrest & Luggage Rack
Kuryakyn ISO Deluxe Brake Pedal Pad
Kuryakyn Flamed Floorboard Cover
Kuryakyn Adjustable Cruise Peg
Kuryakyn ISO Large Male Mount Pegs
6,000K Xenon HID Kit
Carroll Leather Saddlebags
Wolo Bad Boy horn