Norm Hamden's car is competitive and street legal.
See the article here.
http://944spec.org/944SPEC/content/blogsection/1/9/5/10/
In the back ground you can see the motor homes taken to Miller. Norm Drove the 700 miles like this after taking a first and second place
So you can find street legal competive cars.
Also Rich Geislers 03 car that got a first and second place this January is street legal.
However it may be hard to find all that in a current car for sale.
You have two choices. 1) Buy what is out there that is well priced and has most of what you want in it. Then either change what is not quite right or live with it.
Option 2 is to build one to your specs from the ground up.
BTW... street legal can mean different things in different states as well. Here in Az as long as it looks like standard road car and can pass emissions every 2 years it is ok. We don't have inspections. Norm is lucker than most since in Sedona where is from there is no emissions testing.