My experience is from The Manx with a win and podium finishes from our late rider Neil "Kenty" Kent, bore and stroke were checked - a lot easier on a lovely little 2-poke 250 and being a purpose made racing engine other than cc there was nothing else to check for, not knowing enough to comment defo on the internal spec rules on a Supersport 600 I don't know how far down they take the motor unless they are looking for specific components and what spec apart from bore/stroke the internals - rods, crank, valves, pistons. rings etc have to be, just taking the rocker cover off would be enough to see(black) coated buckets/followers whether you were looking for them or not.