This is my take on the Space Flight Chronology
Baton Rouge class cruiser, which is the immediate predecessor to the Constitution. I personally belive the USS
Republic is a member of this class (as there's no canon evidence to suggest otherwise.

)
This is a collection of what I've done so far. Please refer to Steve Pugh's
Baton Rouge page for what I'm trying to get at. Note that I'm only going by the 3/4 drawing, as the schematic doesn't really look that good. (Try downright disturbing

)
The original forums is at SCN
Starship Republic NCC-1371 - Baton Rouge Class so take a look.

Now, here are the most recent/relevant pictures.
Top
Ventral and Side w/ Nacelles (old WIP nacelles, just ignore em'

)
So, whaddya think?