I would worry much more about proper adjustment, then check the max rpm to make sure it is not exceeded. Many 266s were done in because the throttle link would not allow the butterfly to open all the way and the adjuster leaned it out to get to 12,600.....
Hold the saw full throttle, not running with the top cover off and make sure the butterfly is wide open. If not, just insert a screw driver in the throttle link and bend it.