Hi man, I recently decided to do the same. I bought a cheap(cafe racer looking) 50cc motorcycle and a conversion kit and a battery. To make your life easier I'd recommend buying a conversion kit that comes with a motor. I bought a 72V 8KW conversion kit which should give me around 11-12 horsepower and top speeds of up to 110kmph. Not the fastest but enough for me. I haven't installed the components into the frame yet but I tested the motor and is looking good. Now it's just a matter of putting everything in and figuring out how to wire in the ignition and the fuses. The conversion kit which basically has everything you need including the motor cost me around 2000$ in total. I can send you links to the kits and the batteries if you want.