22C. You do not have to specify a base classic style as there is no base classic style. You can provide some information if you want, and I would. In this case it is probably simple and effective to just call it an Arrogant Bastard Clone. If you live in an area where Stone does not distribute and think judges are not familiar with AB you can try "IPA strength dark strong ale" or something but I think most BJCP judges are familiar with AB.