That's small, there are bigger cities. It may seem big, but there's hardly anything in it. Just a couple of tinkeries and a bunch of filler structures.
Other cities will be more difficult, and they have other stuff you'll need.
I haven't tried this yet, but I have played with tornados in the past (Atonement modpack). Are you sure you want to go with it? It makes things impossible to build on the surface, and the areas around you become a crappy wasteland pretty fast.