The street bike 600s aren't very close to the FIM supersport machines but are actually pretty damn close to the AMA machines. The WSS machines are allowed more suspension mods and can do more to the engine internals. In the AMA the engine must retain OEM parts, clearences, etc. No metal can be removed from the inner surfaces. You must retain OEM fuel delivery components, stock wheels, rotors, calipers, etc. There are some things that can be done to retune the suspension but not much. Having a full crew with no real job other than optimizing the race bike is alot of what makes the factory SS bikes that much better not to mention the riders aren't worrying about money and having to wrench their own machines.
There are some scams that the factories pulled in the past that have been cracked down on somewhat. They have had those "special" parts avail. from the factory with the part numbers "hidden" somewhere in the OEM parts list. If you were able to find out the numbers a asked for them you would be told, "Sorry but those are own back order and will not be avail. until October or later. Kawasaki has done this in the past.
The HP numbers I've been told on the AMA factory 600s is aroun 116-120rwhp. The engine guys are pretty tight lipped about it.