cylinder kit with new long bolts new cylinder cowl new crankshaft (old one wont fit new kit) new carb and manifold (min 19mm) new exhaust (old one wont fit) ideally new bearings and seals new gasket set probably new clutch depending on the kit you go for upgear kit to make best use of new power
there is an italian dealer on ebay that does a package for a good price, you will just need 125cc exhaust on top of this