If my math is right, and I'm not sure since I seem to have misplaced the measurements, it's about 585 meters long and 96 meters in height.
One thing to keep in mind is that the universe my story (which starts in 2383) takes place in is not the standard Trek universe. It's a parallel universe in which Starfleet is a tiny bit more military. In fact, it's explicitly identified as the naval branch of the Federation Armed Forces. It's still a science vessel, first and foremost, though. In essence, it is kind of to the Sovereign
what the Nova
is to the Intrepid
, thus the similarities in appearance.