Seems I read somewhere that if the car is virtually identical to the 81 model, that a later year car could be used in Classic category. As someone mentioned, 81 is a year that was picked to cut off newer cars that had an areo advantage. If the aero is the same for the 82 escort as the 81 escort . . seems to be no unfair advantage to fit the 82 with the 81 trim and "presto" you have an 81. But I've been wrong plenty of times before.
And considering the Muscle car angle on this, . . . . was the Vega in production trim really a muscle car? Should Vegas be banned from Classic?