"Seriously, massive guns, lots of them, "
What you really want are the new generation railguns that are kinetic energy devices you can maybe rapid fire if you have a big electrical plant.
Along with the new guided ballistic shells, oh yea. Anything and everything. Just a massive beast. And if torpedos are a problem, then solve it. Swarms of robotic defenders woudl be cool.
if we don't currently have the workers to produce such a ship, then make them. The workers who did it in the past weren't born with the knowledge. Anyone with that type of thinking should be careful... they've sipped one to many lattes.
Grow a set, say 'we will make this happen'.. then start working on getting it done.