There are lots of options, it all depends on what you want from the scooter. Will it be for everyday use, are you going to use it on the street, and how much? What kind of top speed do you want. Etc
Also its important that you tell us as much as you can about the scooter. Otherwise people cant really help you.
So can you give me a full part list, of everything that is on the scooter right now. And the amount of kms it has run. And your wishes for what you want to do with the scooter, along with the experience you have. Are you comfortable changing the cylinder and crankshaft yourself, or would you need to go to a shop.