Still working on it:
http://img245.imageshack.us/img245/3411/starwolves6.jpg
It is possible to add GKTurrets to Motherships (I mainly did this modification to test that), the problem is that the GUI infestructure is not in place to handle them, this means that you cannot equip or unequip them, so you have to not only spawn the mothership with them already equipped, you cannot swap em around as you need it.
The reason why I picked the Lion in particular is that, the Left/right turret mountings always felt like they were meant for a much larger turret. It seems like the developers may have originally intended the Lion to carry GKTurrets, considering how perfectly they fit.
Now the Lion has 2 GKTurrets, 4 GKGuns, 8 Turrets, and 8 Systems.