NewyorkKopter, There are tons of places that can fabricate a chassis to support the Hp/Tq figures you are quoting. Many, many lambo replica chassis are already capable of that and you can just order one and be done.
Your bodywork question is too open-ended to be able to answer it. Are u providing a 3d design that is ready to be cnc'd? a couple of sketches? do you know the dimensions and all of the specifics for the detail work? I guess what I am trying to say is this: When you build it yourself, you can afford to spend as much time as you want making changes and tweaking things and you will get the product as you envision it. If you hire someone or some company to make it for you, then you either give them exact and specific details on what you want in the form of cad drawings, or you constantly make changes to their work. If every hour of someones labor is going to cost you $45, then how many hours can you afford before you say "NO MAS!" ... It might be completely open ended! Just depends on what you want and how many compromises you are willing to make?
Hard material costs for making the mold are over $10K