I looked at this kit thing for the Hayabusa in the Mini. Really it would be much easier to simply build a tubing chassis and mount the bare sheet metal body to it. You could retain opening doors but the rest of it would be much simpler to just use Duzs fastners, body sheet metal, and be done with it.
In any case this is just like building a race car similar to a pro stock. Not as complex but still all custom. A big problem is the rear end and transmission. These need to be small and compact but have some hp rating or you will bust them. Remember these motors have about 175 hp stock.
You need a reverser. This can be an electric starter motor conversion but it still is kinda complicated and you will need some machine work. This is a flakey way to do it but it works for reverse only and gently. The jack shaft and center transmission with independent a-arms like we used is almost all fabrication and only a small amount of machine work. But you need some engineering savy to do it right. The chain is over $125 and you will need 2 of them. Same with the front end. You can use ATV spindles with some modifications like brakes and relocated drag links. It goes on and on. It can become a real money pit as everything will be custom. I don't think you could do it for less than 15k not counting the motor and body.
You will need some serious car building skills, very good welding skills, preferably TIG welding, a Tig welder, a good drill press, good saw, possibly a band saw, a very good hand drill, good 5 in grinder. Well stocked tool box. Just for starters.
