Udo and his younger sister Helmut
Yes you are right - I never had the chance to dyno Udo's engines and this is the reason why mention him explicit at this point.
The bikes where fast and yes you are right again power numbers today are harder to get since correction factors and norms where making them much more conservative.
When I started I was trying to get all available information about the B+S bikes as well as of the very very fast Wolfgang Schnepf engine - which I consider the strongest at that times with 1000ccm during the wunderful bot years.
Wolfgang was a young innovative BMW Ingenieur that times and later worked for Porsche in Weissach. We met each other at a race in Oschersleben and stayed in contact since I work for Porsche on a loose basis as an instructor since then.
Tell Udo and his sister Helmut that he should not go for the roller cam - I did all this and still have all parts on stock....but for a lot of reasons it is not the way to
the holy gral. Flat tapped cams are easier to get modern profiles on.
If he is trying to get nascar technology, like some guzzi dudes did, inside the flat twin tell him it means 17 mm valve lift or even more which will not fit into the rocker geometry at all, beside this you calculate the lift in approx 28% of the valve diameter...so this is also a question to be answered.
So better using a current racecam, mushroom lifters if necessary....etc.
If he wants to take the next step - our all new developed billet heads are around the corner.....not thinking this is right for a vintage R 90 S.
Best regards to Udo and Helmut !