The '07 GO 129 may surprise you with it's performance as a slalom board.
Will you win any slalom competitions with the GO 129?.... probably not.
As far as putting a cambered sail on the GO 129, that should not be a problem,
but since cambered sails tend to cost more, one wonders if the additional cost
will be justified.
There are plenty of free race sails (both cambered and no cam) that will give you
the power and stability to extract the full performance from the GO 129.
Will it work, yes!
Is it a good idea..... maybe.
Hope this helps,