The 500s will be fine. Or they're the right value at least. Cant tell the quality of the pots from here! 550s from BK are just supposed to add (or allow, rather) that little extra bit of cut and clarity from high output pickups.
As I said any pickup will WORK on 250k, 500k, 550k, 1M pots, its a question of how well matched they are. The higher the value of the pot, the brighter the sound, up to no pot at all and direct to jack wiring, which is the brightest, highest attack sound you can get out of a pickup.