If you've ever raced a bike with a featherbed frame, you should know how important the weight distribution is. With a Triton, even though you can get the motor well forward, a manx will always handle better because of where the motor sits. Back in the 50s, there was one Victorian rider who raced a Norvin, and was able to win races against the manxes - why would anyone bother ? A big blast on a vastly over-capacity bike does not prove much. It was something which set a precedent in Australian road racing, and a reason our current historic classes are so stupid. There was a race bike 880JAP/featherbed racing here about 12 years ago, it was not something that I would ever try to ride in a race, a triton is bad enough. It is easy to find yourself in a 70 MPH corner with the bike feeling vague in the front end and twitchy - it really destroys confidence and stuffs your riding technique.
Those sidevalve motors in featherbed frames are the way to go - probably would not bite you.
I like this better:http://www.youtube.com/watch?v=UbUrIwA9jVE