The thing with the Split P is that you will lose a lot of the "character" that makes a P-pickup sound like a P-pickup. So are you after aggressive and growly classic precision sound, or aggressive and growly modern sound?
Assuming you are looking for P character with more attitude and growl, my suggestion would be either the DiMarzio Model P (since you seem to like DiMarzio from your initial suggestion) and the Seymour Duncan Hot for P. The SD has some finger noise that doesn't seem to be an issue with the Model P from DiMarzio. The Model P will have more midrange content and also has adjustable pole pieces to even out tone and response as well.
If that's not what you are after, then just slap some EMGs or active S.D.'s in there. If this is going in the BC Rich then the EMGs solid black color may match it better and emulate the vibe of that instrument better than a traditional pickup might.