good, now that we have this thing settled, may I ask the lord what are you trying to achieve?
I mean, are you shooting for a specific race class?
I am pretty involved with modern bikes too and currently there's a real avalanche of new, very sophisticated V-Twins out there, KTM(super compact), Aprilia (new 1200 engine shown), Moto Morini (a real beast and also designed very smartly), Buell, not to mention Ducati that churns out 150 in street trim, 200+ in race tune.
So as a design and mfg exercise this could be cool, to beat factories that use pro fluiddynamics 3D and 2D calculus/simulation, can test endless combinations of pipes, airboxes, cams, whatever is a tall call.
its sad, but the days when someone like Britten could challenge the big names with a home made effort are gone IMHO. never mind that he had pretty serious resources form his real estate dealings and that many of the people put endless hours into that project without pay (Just happen to know a guy who was involved, he said john was hugely charismatic when having to pull people into the project).
That said, I would definitely go for CAD as with old school tooling, the wood patterns are your only documentation and changes are hard to track or implement.
I happen to spend a lot of time designing in 3D and I would estimate quite a few hundred hours just to build a motor to a basic rough level, well above that to start sending out part files to contractors.
Expect to have a learning curve of about 2-3 months until you can get really prolific/effective with a top shelf 3D CAD package. You should get to a level where its responds like a hand tool and you have no limitations as about how to build parts. The basic stuff is easy but when you get to high level surfacing you might want to look into some training.
Hope it will be an easier starter than the CR750 when its ready
Will be happy to contribute my knowledge.
TG