I thought about this some more and got to thinking - I mean, technically you could put any kind of pickups and any kind of wiring into any kind of guitar you want...
If you wanted, you could rip out those pickups, put in 2 'buckers and a single coil and just throw a normal 5-way switch in there and change the 3-way to a mini toggle to split the 'buckers.
But in this case, the 513 is all about those pickups and that switching capability. Take that away and you no longer have a 513 - you just have a sweet PRS with aftermarket PUPs in it.
So i guess to simply answer your question, you could put whatever pickups in there you want, but you probably will have to change the rest of the wiring, too. But, it could be done. I mean, I don't see why it couldn't. It just wouldn't be a "513."