please take the oto 127mm gun from this sheet here
http://dl.dropbox.com/u/63276563/belowdeck%20guns.png where do people keep finding those outdated parts?
btw, for some reason there are quite a lot of horrible pixel artifacts on your drawing. if you zoom in you see that no 9 adjoining pixels are exactly the same colour.
I still think the ship is on the small size for 2 Mk 10 GMLS (you could get away with it on a hull the size of the USS leahy, but that ship had 2 guns which were together less then the weight of the compact, fitted amidships to keep the bow and stern clear)
the problem of the systems fit will become apparent when you add the needed directors forward as well.
keeping all that in mind, I suggest removing the forward GMLS and instead install an ASROC box launcher. the aft launcher would best be an horizontal loader as well, instead of the diagonal you have now. try to place the torpedo tubes amidships, and 2 phalanxes should be enough (the phalanx was actually designed way later then this ship). this would leave the deck on top of the Mk 10 available for vertrep and maybe even helicopter landing.
that said, you are learning, I can see that! keep up the progress