First, I've been using the AMT kit, which, after converting 141.72 m to inches, and dividing by the 10.5" width of the kit's primary hull, comes out to a 1/531.38834. Drawings (1/2000 scale) for Constellation class Star Cruiser, can be found in Jackill's Star Fleet Reference Manual Ships of the Fleet volume II. The primary hull is deeper, and larger in diameter than the Enterprise. These dimensions are quoted from Jackill's.
Enterprise: Primary hull length; 146.31 m width; 141.72 m height; 32.94 m
Stargazer: Primary hull length; 205.18 m width; 161.88 m height; 50.91 m
The extra width, 20.16 m, is an extension of the primary hull, an added ring outboard. the extra height will require adding material between the upper, and lower hull halves, 17.97 m more.