I know just how it feels to have very few guys
my high school is just the same way, only we have about 3 very talented girls, too
I would suggest 'Bye Bye Birdie'
We just did that, and it was pretty good
we were somehow able to get some of the guy friends of people in the show to help out for 'The Telephone Hour' and the whole shriner scene, and Randolph (Kim's younger brother) can always be changed to a younger sister
other shows that have very few males are SMILE (it floped on broadway, but has great music, and almost entirely female cast), and 'She Loves Me'
Let us know what show you end up doing, so i can suggest it for my school as well!