RM dd-ca has never really been balanced. I would still recommend the stock guns for thier amazing reload and having good dmg/shell.

But you can try the 8"/45 EOC "W" gun or the 12inch single 

The zaras guns are pretty much the best non-BB guns that RM has, imo. Fairly accurate, great reload, good damage, good range. The angle is a pain, but theyre great guns. Theyre basically a super version of the 8" duals designed for the bolzano and trento I think.

I continued to use the Zara over the BB0 in GBs until I got the AD.

I too am having issues with Zara's guns. Isn't there like two sets of 8" turret that have the exact same stats? 

I'm using the level 48 8" "Z", but will upgrade to the higher level guns when my spread improves.  

i use the single 10" EOC guns on the zara, it has quite a reach with them, they are singles but you can reach out and hit someone. those guns are low angle if thats more your style.