Well it looks that you already have a few more than capable cars. All you need to do is downgrade one of your cars (power-wise) and concentrate more on the car's handling, which I am assuming is what you are having problems with. Basically, you could win by sticking soft compound tires on, since the race doesn't involve tire wear. The 3 cars that you mentioned are all heavy, so weight reductions would benefit nicely as well. If you are using the 3000GT, which is a 4WD car, you can buy the Variable Center Differential (VCD), which allows you to control how much torque goes to the front wheels. Set this low to get more power to the rear wheels, which would help in the car's maneuverability and loosen it up to get around the turns easier.
