The original Featherbed frame could house a variety of motors. A new Triumph with the 270 degree crank would be sweet. I stayed with the 750 Norton motor for mine, But changed most everything else, which was basically the front and rear ends. Koni shocks were the order of the day. Rickman also made a sweet frame similar to the Featherbed. The fastest of those years ago was one with a 900 Kawasaki motor. It ran about the same top speed as the 4 cylinder 2 stroke Yamaha road race bike.