The front shocks n springs are a straight swap from a k11 but not the hubs or the wishbones, modifications are needed for that the work. The best gearbox for racing would be the short ratio 5-speed (identified by the code on the flat part at the top behind the bracket for the clutch cable), the code should have an A5 at the end of it (i think, the 4 means long ratio).
Was the ma12 you're using a cat set-up? If so converting to the origional non-cat carb set-up will help it out, and you can use a standard 1.0l carb for that as the ma10 carb has larger jets than the ma12 carb. Oh and by the way if you have any other ma12's with a long ratio 5-speed attached that you don't want, let me know.
