My wrist pin circlip decided it wanted to break in half this weekend, and damage the cylinder, VHM flat top piston and head insert on my K9b. So I am in the same boat as Anthony, my rules also allow mixed homologation. I am thinking about doing the KZ10c cylinder, VHM FT piston, and KZ10c pipe.
Can I ask why you run the flat top piston? From my understanding changing piston design can change the dynamics on the engine in a negative way unless you also change head shape and possibly the pipe dimensions. That’s what kept me from running the RS piston in my Honda 125. Do you get better results with the flat top? Seems like with a bigger combustion chamber you would have less compression so less potential power.
Now I have another dilemma. I was just offered a fresh complete K9c with all the running gear and a spare cylinder is included. That would pretty easily give me 2 engines ready to rock. Now I can decide if it’s worth going that rout, or upgrading my top end to the KZ10b/c to get the better power and more current parts. Cost either way would probably be the same.