You're not going to (officially) get H2R camshafts, or any other H2R specific parts, for your H2. You might, on the other hand, be able to get aftermarket camshafts from Web Camshafts or some other suitable source, if they have something that will go in. Given the miniscule number of such parts that they are likely to sell, I have my doubts. But perhaps a bit of research on the dimensions of the engine compared to others of similar size and arrangement (zx10r, etc) might turn up something with compatible cylinder bore spacing, journal diameters, oil flow passages, etc. It will cost something ...
Now, having said that. We all now know that the H2 is a monster right from down low in the RPM range and has a very steady progressive torque curve resulting in big power everywhere. It makes monster torque down low because it has conservative cam timing (because the centrifugal supercharger isn't contributing much yet). The conservative cam timing costs power up top but the boost pressure MORE than makes up for it. If you put wilder camshafts in it ... sure, it will make more power on top, but for a street bike, a vertical torque curve that starts with (relatively) nothing and then has a massive increase might not be very user friendly ...