The "Rule of 96" is a rule of thumb - a very big, wide thumb, at that. Weight whould be what makes the shooter happiest or shoot best. Balance is the factor that determines how much weight goes into each hand. Moment of Inertia is the factor that sorts swing effort for given weight and balance. Since MOI is the summation of weight times radius (from CG) squared, long barrels and long stock have a disproportinate effect, especially if they have dense wood and thich barrel walls.