Actually, to be 100 perent accurate, you should bring the 1971 Charger chassis, since at this time the cars were stock cars as the name says.
They only reinforce the chassis with a roll cage, and got more powerful drivetrain to the car and widened the bodies for wheel clearance..
Race on sunday, sell on monday was the word at this time!!
The race cars must be available as street version with the same powerplant as the street cars.
If the Charger weren't available with a 426 Hemi, so you couldn't race it with a 426 Hemi!!
They change some rules on mid '70s or so when large displacement engines were not available on street cars anymore. or very few!!
The same happened with the chassis!
But the chassis of this kit, if i don't mistaken myself is a leaf spring unit wich is pretty much accurate for a Mopar this year, i would keep it.
Good luck with your project!