Pardon me if I misunderstand your meaning, but it seems you are suggesing that the filter # is equal to a contrast grade. There is no real correlation between a single VC filter and an ISO Range Number. Generally, the higher the filter #, then the higher the apparent contrast. But, it is possible for two filters to produce the same, or very near the same contrast i.e., ISO Range Number, given the particular paper, light source, and developer.
Originally Posted by Bill Burk