I used to have a Gibson Firebird Studio, I think you're right that it's similar to an SG with the set neck and all-mahogany construction. Mine had that dark mahogany tone, but with maybe a bit more "body" than my SGs.
I wouldn't let the AC/DC thing influence you too much, the Riff Raff is just BKP's version of a '60s/'70s Gibson "patent no" pickup. But if you're not keen on that, I wouldn't go for the Stormy Mondays, they'll give you a very classic, low-output PAF sound, not modern at all.
From your decription, "a modern distortion sound, smooth but with plenty of clarity", and given the mahogany guitar, I'd be thinking Cold Sweats... most medium-output pickups can get a bit muddy in mahogany but the Cold Sweats work really well.