What to wear for my Annie audition?

I have an audition coming up to audition for being an orphan or Annie in the playhouse by my house. I am fifteen and can make myself look younger believe me, but what do I wear? I was going to wear overalls and my hair in braids (pigtails), but my dad says that is the total wrong time period and they won't think I have the look. I have my song pretty much down, so now I am also worrying about this. Please help!!!? I can't find a long ugly dress....