I can't speak to rear brakes, so maybe you are right with regards to them.The 500 caliper will work, you will just need to change the caliper retainers if you plan on using a 7mm thick disc .....
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However, with front brakes, what I said holds. This is an SR500 caliper and disc. If you put a 7mm rotor in there, it is probably going to scrape the housing. The U-shaped gap in my pic is wider on an XS650 caliper. The left-side SR500 caliper is a different part number that the XS650 left-side caliper, and this is where the difference is.