Looking nice.
When you say cannon configurations, do you mean number and location, or whether they are sunken, flush or on spars?
I am beginning to think, considering the rest of the elements of the ship, the pod thing on the bottom of the engine section doesn't seem to fit. The rest of the pieces slowly angle in to each other as a continuous block with no spars or anything. That section on the bottom of the engine section doesn't gel with the rest, it gets smaller rather than larger where it connects to the superstructure, and is connected to the rest of the rear segment through another, thinner element. To me, it gives the look that it's some sort of aftermarket booster engine (and the reason it looks like an engine is it has the same sort of overall shape), not an item original to the ship and part of the structure.