Pickguards from G&L can be bought at Chandler (pickguard heaven).
http://pickguards.us/Have to specify the model and state it's an indonesian (different measurement than USA one's so, if you don't specify, it won't fit your guitar). As I recall, you cannot fit a fender cover but ain't sure, gotta check later on, got a loose G&L pickup and a loose fender cover. What I am certain of is the fender cover won't fit S500 pickups. As for the pickups, fender don't use seymour duncan as stock. Usually, american standard are fat 50's. If you want a real humbucker sound, single coil size humbucker won't sound as fat or full. Not even close. They sound great, but far from the full size, different. Having that in mind, they are something else, but sound nice and good. Have a JB jr, like it, sound good, but different. I prefer full size, but it's a matter of taste. Dynamic is different.
Cheers!