i have a gsxr 600 motor sitting in my back yard and a 400 ex that is itching to have a new engine dropped in it. i know the frame will need some modding. wondering if anyone on here has done it or knows anyone who has. wondering what anyone has used for sprockets in the rear and how they got them to fit on there. will i be able to use my gas tank or will i need a custom made one. i would love to keep the 400ex flow going without changing the tank or plastic out. exhaust is not really a big deal. and i have the dashboard for it. just looking for info on what anyone has done to get everything together. and how they liked it.