hey blade, one of your best options for a chassis would probably be a arrow ax8, and a rotax 125 for an engine. I used to have a 100s air cooled, then a 100s watercooled...but u have to many problems with em. With the rotax 125 you dont have to adjust fuel mixtures or anything. A rotax might cost u more but in the end u'll probably save yourself money from not having to rebuild the 100s and plus the rotax is way more fun to drive. If your considering racing u should think about joining Geelong kart club, they're one of the better clubs around vic.