I'd put the engine in front of the seat post. I bought a scooter someone had put a go-kart type rear cut down and a 2 stroke leafblower engine on, it smoked and puked oil but it ran for $20! I put a 2hp briggs on it and it runs great, it's a bit squirrelly on turns due to it not being a live axle but is perfect for swap meets, car shows and the zoo! I ride it all around the neighborhood as well! It goes pretty fast for what it is!