Hello Kevin,
i have the same topend on my black flash (hence my name here). I am using a 36 mm Mikuni VM carb on that engine and have a TP race cam in it. well the one he made 10 years ago. I somewhere have a diagram of the cam.
I had to experiment with the exhaust a lot cause it the exhaust noise which stopped me from getting the bike road registered. It was first fitted with an Armours Goldstar silencer > 121 db. the MOT guy is doing classic racing on a G50 but when he heard the Comet he went pale in his face.
then i tried all sorts of silencers i could get hold of for trial runs in the fields. I finally found a noname readily available one from a dealer on the internet for 50 GBP. which sounded and felt ok.
It also changed the engine characteristics and made it much more pleasing. Before the engine a was real Gold Star RTT2 sort of . madly slipping the clutch , if the revs dropped the engine would die, now it is almost like a standard cam, but with MUCH more grunt than standard Comet.
I went for a Norton Commando N type gearbox, a NA will do as well, just needs a bit more of filing to reduce the width of the g/b lugs.
the clutch I am using is a Commando one with newer friction discs run dry (I am on a belt). due to the horrible engine characteristics at the beginning of my trial period a managed to blue the steel discs just from take offs.
I am still fiddling with the bike now and I won't take it on a dyno before it has done at least 2000 mls, so I can only guess.
but from the way the bike accelerates I am sure it must be over 40, more like 45 bhp. But that is just guesswork.
Hopefully a dynorun will tell that year. But just standing next to the bike and listening to the tick over, which goes bang, bang, bang…. compared to a more likely puff, puff, puff on a standard Comettells you all the difference and dare I say it..give you goosepimbles.
Oh I am also using twinspark ignition.
cheers
bernd