If you are currently running at a sprint track, in Super Sportsman - Super Box (2004 IKF National Class #8), the most likely road race crossover class is...
 
 

NCK Local Option Class #23 - NCK Sprint Super Sportsman CIK

 
Rule Differences...
 

Tires:
 

YDS tires.
 

Exhaust:
 

Any version of RLV SSX muffler (4-hole can).
 

Clutch:
 

Open clutch.
 

Race / Heats:
 

30 minute race.