You could order a factory Hemi Dart in 68 for racing only.
From the net....
Another infamous 1968 Dart option was the Super Stock Hemi Dart. Hurst built approx. 50 cars for competition in NHRA’s competitive Super Stock class. These cars were acid dipped bodies and had fiberglass fenders, and hood. The cars came with bare bones interior and light weight lexan windows. They were built to be feather light and extremely fast from the factory. Each car also came with a four speed or torqueflight mated to a Dana 60 rear end and racing leaf springs. Under the hood was the 12.5 to 1 compression 426 race hemi. These cars were not street legal and even came from the factory in primer so racers would create their own paint schemes. Currently, super stock Darts and the Barracudas run the quarter mile in under 9 seconds at over 150mph.
The most famous package cars ever produced are the 1968 Hemi Dart and ‘Cuda. Finished near Detroit by the first version of a Mopar Upfit Center, these cars were built for one purpose: to win at the drag strip. Equipped with a 426 Hemi in a small, lightweight package they dominated Super Stock class racing and Arlen Vanke won Super Stock Eliminator at the 1968 NHRA Nationals in a Hemi ‘Cuda. With Lexan windows, A100 seats on aluminum brackets, a light weight body plus a cross ram Hemi these cars created a new definition of performance and reshaped racers thinking on what was possible on the track. They dominated the record books and remained competitive long after their introduction, so much so in fact that NHRA created a special class for these famous Mopar’s: SS/AH. Today the class run-off at Indy is simultaneously run as the Hemi Challenge Race sponsored by Mopar. Still drawing large crowds with tremendous fan support, these now 1000 plus HP racers show no signs of disappearing from the competitive scene.