Get the 75 cc kit It works great. If you want all out get the oversize intake and the 17 mm Amal carb on our site. It is a great combination with that kit . For the exhaust you can go with the Polini morini exhaust and slightly modify it if you have the large fan Magneto. If you have the small fan you will not need to modify it at all.
For the sprockets we have 9,10, and ll. that will fit right on or up to 14 teeth (will need to modify case if you go that large. Also have rear sprockets as well but need to know which wheels you have (3 or 4 sprocket mounting bolts)
Chris MWH