The 650ss MUST be kept totally original.
The wideline frame is the best so fit the 750 motor in it. Front forks and wheel/brake must be as light as possible for the best handling on the racetrack so junk the heavy roadholders and fit some lightweight Marzocchi forks (I used the forks and 18" WM2 front wheel/double sided brake from a mid 70's Ducati single - they are much better than the Norton items, have the correct springs and damping and are allowable in Classic racing). Only consider the Ceriani if it is a lot lighter than standard Norton parts. Use a small front racing tyre, 3.25" or equivalent, bigger ones just spoil the handling on Nortons. I tried a 230mm 4LS Grimeca wheel but it was far to heavy and spoilt the handling (fortunately I still have it as those original ones are now worth a fortune!) Using 18" wheels and 60/90 rear springs the rear end will have to be raised at least 1.5" to keep the frame off the ground if you intend to corner at proper race speeds i.e. close to 60 degrees angle of bank. Use longer spring/damper units or lower the top mounting lugs on the frame. Junk the rubber bushes in the swinging arm and replace with Manx style shouldered bronze bushes with a spacer between them. The bushes and spacer are clamped between the frame tubes and the swinging arm pivots on the bushes (size them so there is no detectable play), the shoulders controlling end play. Aim for 300 lb max weight. Finding space for the exhaust is a problem on Featherbed frames as there is no room in the conventional position if you want to corner at crazy speeds, and who doesn't? The only options are high level pipes or two into one under the engine with single megaphone exiting under the gearbox, angled up past the swinging arm, being careful to ensure nothing can ground. Footrests, brake and gear levers present similar grounding issues so MUST be mounted several inches higher than you think is necessary. Finally I come to the oil pump. Most Norton heavyweight oil pumps are worn or assembled from poorly selected parts resulting in excess clearances. In extreme cases at continuous high revs i.e. when racing, this can result in the oil being fed to the engine faster than it can be scavenged, with the inevitable consequences. To avoid this the pump gears must have a no discernible end clearance but be free to turn when the pump is firmly bolted into the engine.
