I've seen people mount some cap-ship weapons, mainly Liberty Gunboat turrets, but Kusari Destroyer turrets are lvl 9 too.
The only problem is a Large Train can only fire 2 or 3 times if it has all it's turrets replaced with Gunboat or Destroyer turrets.
Maybe the energy level of Transports and Trains should be increased? Then fitting other weapons, such as the Liberty Gunboat and Destroyer turrets, would be possible.
