Based on a preproduction design by Rick Sternbach for the T'Pau in TNG:"Unification"
The main body slopes up to a height of 5 decks. Assuming an average height of about 3.66 meters per deck, the ship would have an overall height of some 40 m, a length of nearly 100 m, and a beam of 56 m.
Here are a set of views at one pixel=one meter:
Some thoughts while scrutinizing Rick's drawing to translate to 3-D. These may be considered politicking for the design, so come to your own decision before reading further.
The deign seems inspired by the Long Range, "Vulcan" shuttle from ST:TMP under the impression that it is a native Vulcan design. It shares similaritites with that ship and with the actual T'Pau, which came from further refinements along the same lines. It also, interestingly, shares features with a fan-designed, Vulcan shipyard-built civilian fuel carrier of preST:TNG-vintage. The "angled front" is also a design feature of the Vulcan designed Karekh-class explorer from FASA.
It compares well to its science vessel contemporary, the Oberth-class, which is four decks through the main saucer. It also compares well with later science vessels such as the Raven [no page available, see VOY:"The Raven" and VOY:"Dark Frontier" I & II] which is some 85 meters long and 4.5 decks high, and the Nova-class [see VOY:"Equinox"] in the range of 140-170 meters long and 8 decks (35 meters) high.
It can't be seen clearly on this model (I'm working on it) but the deck under the bridge has a set of large windows facing forward, a feature later seen on the Intrepid class [no page available, see any Voyager].