I know a few custom builders who are taking this direction. They take a big American V-Twin and stuff it into a sport bike chassis that they hand fabricate. But it’s always for a one-off project. As the opposite, the idea of Curt Winter, owner and designer of Big Twin Racer, is to offer a ready to assemble aggressive riding style sport bike chassis accepting most of your Big Twin components. So he designed a rubber mounted frame with increased longitudinal ridgitity by the use of a unique perimeter style double backbone. Rear suspension is single shock. Critical components such as oil tank and gas tank are rubber mounted so that over time vibration won’t be a problem. The gas tank is also is shaped to fit between the twin backbone and give free movement to the rider. Oil is carried in an aluminum oil tank, mounted low and in front .to lower central mass weight and increase oil cooling by grabbing fresh air from the front. You can buy the kit or ask Curt to assemble your components. To see how it would look, go to War Horse Big Twin..