Why does it only have to be gearbox and wankels? My 2c is start with it open and see who comes.
KF is like a Rotax Max on steroids. Single gear, 219 chain. KF2 makes about 32-34 peak HP. Times are usually on par with a Stock Moto. I figured since you have the Aixro and so on in the list, you might as well throw in KF as well thats all. I like the idea of the class. Would be cool to see all the different types of karts duke it out.