why do you feel you need to rebuild the carbs .. they just may be perfect as they are .. try it before you waste your time rebuiding them .. I have bought many old skis that have sat for years .. many years and most have not had any carb issues ..i just drained the old gas .. dropped a few extra drops of 2 stroke oil down the cylinders and then primed the carbs with a squirt of gas ... with fresh gas in the tank .. away they go .. if it was put a way properly .. that ski should be fine as it is ... just get yourself a good battery and ride !
I rebuild every carb on every ski I purchase.
I am TREMENDOUSLY obsessive compulsive, though.