That sounds like what used to be called "Triumph Day". I went about 15 years ago and had a great time. Pick-up trucked the bike along with wife, kids, and camping gear and made a long weekend of it. many really nice bikes, and the roads/scenery in western Mass. were impressive.
If you look around, like BritBike Forum, you'll likely find details.
Dave, hers's another happening on Sunday.
Vintage Motorcycle Day, NEW LOCATION!
Sisson's Diner, Rt. 28, South Middleboro, MA No cover, pre-1976 bikes on display!
508-279-2700