Hi,
you could contact CJC Principal or their gymnastics CCA teacher-in-charge directly on your request.
Bear in mind that the only risk is (if you dont plan on repeating J1) that the curriculum being taught may be different as different schools start with different topics (i have no idea why there isn't any standardisation).
http://www.cjc.edu.sg/cos/o.x?c=/wbn/pagetree&func=view&rid=1081777
i was in this sport as well
the max for guy is erm, 25, for international levels.
anyway, does it matter which JC to go in order to make national team?
my era was long long ago
good to have aspirations
wish u luck.
have u checked with ur current principal and CJC principal?
J2 then transfer?
might be quite tough
or they might need u to retain
unless ur results can prove otherwise.