A couple of suggestions - Every fall the Antique Automobile Club of America has a huge meet in Hershey, PA. I've seen a few motorcycles there through the years. Unfortunately you missed it this year - it was last week. It's huge, though!
Something else you can try is Jpmracing302.wix.com/jpmracing. Jim Rice organizes events. He might be able to point you is a good direction. Good luck in your search and post up some pics when you get your hands on one.
Thanks ill give him a shout, to bad I missed the pa meet.