If we go about it according to those times, where ladies could get married as early as 15~16, Kongou might even be old enough to be Akagi's mom.
More amusingly, Tenryuu, Tatusta, or even tiny destroyer Satsuki could be Yamato/Musashi's mother. (For that mater, any of the -tsukis could be, including Uzuki or Yayoi.)
I also kind of like the idea that Myoukou class are the daughters of the Kongou class. (Kongou -> Ashigara, Hiei -> Ashigara, Haruna -> Haguro, Kirishima -> Myoukou?)
