Re: Replacement of 22 fret on my Ibanez
There are lots of threads in this forum about converting from one neck type to another (22 fret to 24 fret; non-AANJ to AANJ, etc). I'd suggest a search. But the bottomline is that this is not a straightforward conversion. You would almost certainly be better off starting over with another guitar -- especially since you're not happy with the tone either.
If the guitar is near new, why don't you try swapping it for an RG at the store you bought it from? Or sell it and look for a used RG? I think the 24-fret RG520 (last made in 2001?) would be the most similar to the S520 (mahogany body, HH pickups, LoPro), and they pop up used and reasonably cheap. That guitar was very well regarded here at JemSite for "most bang for the buck."