Don, you can thin the sprockets in a lathe. Rears are easy, front is tougher, can be ground and measure carefully.
If they are surface hardened you may break through so might be better to buy a front. Make sure you radius or bevel tips, just like the side you left.
Yes you can do that, but only try it with rear sprockets. Front sprockets can be a lot harder than rears and are more likley to shed teeth under load. When i used to work for a Ducati shop we found that even using non genuine front sprockets could be a problem with shedding teeth
On your 500 i would run a decent DID, Tsubaki, EK or other quality "O" or "X" ring chain in a 520. It may cost a bit more at first but it will last a lot longer
And John Burk, belts and various size pulleys are a whole lot more expensive than chain and sprocket combinations, they are also a lot more sensitive to alignment
Gray