What you need to buy is a kit car.. go to
www.factoryfiveracing.com and look at the 427 Cobra Replicas. They run on the Ford motors/trannies/rearend, and are HIGHLY customizable. They will end up faster, lighter and handle better than anything you have driven. Probably VERY fun to build and 10,000 less headaches than you trying to ENGINEER something from your car.