If you're thinking about resale value some day down the road, there are two reasons why this doesn't really matter so much.

1) Soon after you have the car in your garage, instead of the wrench's (yes, it will happen some day), you will come to the conclusion that you will NEVER sell the car. If you want something different, you'll just get it and have 2 P-cars.
2) If I'm wrong (see #1 above), the new owner will take delivery of the perfect American car and within a week it will have H4s, ride a little lower, the works.

But as the others here have said, only do easily reversible upgrades to the body. And remember, even a viper green coupe looks a little ho-hum with the American headlights. The H4s and a lower ride will give it just the attitude a vg car needs.