Idk, We don't have to do the dice system. The downside to using that would be that Class A would be on the same playing field as Class F. The whole point would be that Class A is supposed to overpower underclassmen in just pure test scores.
Alternatively, we could assign some point values based on classes and combat would work something like having to beat the opponent's scores using some type of boost or ganging up. I didn't really think too deeply into that one yet. This system would favor more "strategy" in character.