Someone needs to look at class rules.
By converting it to a 1972, you would have to run a low compression 340 & a 727 trans. in a NHRA stock class, that is if they would let you run the 1970 side marker lights.
I have a friend with two NHRA Stocker Dusters.
He used to have to change the rear bumper to run the car as a 1973 (340) or as a 1974 (360).
The car was actully a 1973 340 car.
You could run it as a 1971, if you wanted the Thermoquad.