I'm not in Germany, but welcome. It seems to me the easiest honda CB's to get into vintage racing with are the 350's and 175's. These small bikes are fun and somewhat cheap to get into, part of the fun is the fact that they aren't especially fast, but that induces skill and to some points makes these classes quite a bit safer for new racers. I myself would like to get into vintage racing once I find the right bike and have the money to do it.