520 Conversion?

[David and Sumudini Guyer]

Been quiet, so here's a bit of a noob question...

I recently got a 46-tooth sprocket.  I have 13K+ on my stock sprockets and
chain, so conventional wisdom seems to imply I should replace them all at
the same time.  Okay, I got that.

Does it make sense to do a 520 conversion?  Am I right that the rear
sprocket only comes in a standard width, or could I have a 530/540 (or
whatever) rear sprocket?

In short, what's the story here?