Lots of details about the USS Centaur can be found HERE
, along with photos of the shooting model - which was actually labelled "USS Buckner", and was covered in windows unlike the inaccurate CG model (created for the Star Trek Fact Files, I think)
It was made from AMT Excelsior (saucer, nacelles) and Reliant (bridge dome, torpedo launcher, roll bar) model parts, plus a ton of greebles. The ship is either the size of an Excelsior saucer, in which case the bridge module would be akin to that on the 2009 Enterprise (where the bridge itself is a room on the lowest level of the structure, at the front of the deck), or perhaps the saucer and nacelles are half the size of those on Excelsior and the bridge module is the same size as that on the Miranda and Constitution (prime) classes.
The ship appeared in the DS9 episode "A Time to Stand"