If you sink $15K into the body and paint for a 1971 Duster Twister, you are way under water on the value of that car.
Personally, all a Twister was is a 1971 Duster with a few pieces of trim and some decals.
Mechanically, nothing sets a Twister apart or makes it perform any better than any 318 Duster, stock for stock.
If you have to have some tape stripes, why not buy a car that was built strictly as a high performance car from the factory - a REAL Duster 340.
Just my opinion, any 318 Duster, Twister tape stripes and fake hood scoops aside, is just a 318 Duster.
If it were me, you know where I am coming from. Spend the $15K on a performance car.
Buy either a 340 or 360 Duster and you will be happier, if you care about performance, instead of tape stripes.