There's lots of guitars with pickups other than what the manufacturer originally installed, just the nature of the game. And of course, there'd be no EMG without Alembic.
In fact, I often wonder why none of the custom builders would let you choose from a menu of circuits/pickups: Imagine spec'ing a guitar and having the choice of Fralins, Duncans, EMG's, etc. Seems obvious to me . . . .
I'm not crazy that this 70's S1 is no longer stock, but then again, if they didn't work for what he wanted, that's his business. Musical instruments are endlessly recycled and modified to fit someone's taste, and at least it's not one more LP or Strat, where to me it's a lot like Harleys: Let's all buy the same ride, wear the same clothes, look the same, sound the same, so we can show the world just how DIFFERENT we are !
J o e y