Starship sizes

Hi all,
   Finally getting back into the groove of doing some kit-bash
design starships and with all the fuss of scale I wanted to see
if what I plan is acceptable size wise.
SDN = 5-6 inch
CV    = 5-6 inch
DN   = 4.5-5 inch
BC    = 4.5-5 inch, thinner than DN
CA   = 3.5 inch
CVE = 3.5 inch
CL    = 2.5 inch
DD   = 1.5 inch

Are these to far out of scale ? Considering I plan to cast my own
stuff I dont want these to weigh a ton but I want them comparable
to existing scales.

Also, is there a FT editor out there that takes into account the 
Fleet books for the Mac ?

Thanx,
   Kirk