I can tell what I'd probably have done, if it was impossible to find any concept, since this thing is really low poly with a couple of textures placed almost randomly.
the rear element is obviously an engine. make it so that it look like an engine, not an unrecognizable brunch of polys.
The nozzles are good, I just don't like the surrounding model.
It's the same of the original model, and this is the problem. Forget about "pick the original model and just add small details" since you can't do that with this ship.
Just use the original model as a general shape/proportion reference.
Then look at the connection between the engine and the hull.
Don't try to reproduce the details of a tiled texture.
Think instead at what
guys would have done if the had the possibility to use 6-7 times the polys they used on their model.
I can imagine a group of pipes, maybe asymmetrical, connecting the two parts of the ship, maybe with some kind of superstructure. Something like a nebulon-b in starwars, for example.
etc,etc..
what I mean is that you can't simply go rounding some edges and adding small details here and there. It's a lowpolymesh, with no details at all, nor in the model nor in the textures.
Think at what the model should have been, and not at what the model is.
Being the textures tiled, make it impossible for you to see "real" details to reproduce in your model, but also gives you an higher degree of freedom.
