I’m sure these improvements are already in the works but if not here are some suggestions.
-Replace the Cruiser class ISDs with Victory Star Destroyers.
-Make the Capital Imperial class ISDs larger in scale; nearly double the size, victory star destroyers are around 900 meters (ISDs are large ships, approx 1,600 meters). I noticed that the dreadnaughts are nearly the same size as the ISD and those are supposed to be 600 meters in length, anyways I'm sure you guys get the idea 
-Make the Victory SD II and Imperial SD II a researchable upgraded ship. From all lore that I have encountered, Imperial class star destroyer II’s are always better ships (not just a ship with alternate stats as seen in this mod).
-Add a criminal faction might be nice (ex. The hutts, zaan etc. or something comparable) and maybe another one from the extended star wars universe.
-Maybe some star wars models for the laser emplacements/missile platforms
-Buildable space colonies like the ones seen in X-Wing alliance that add logistical support to the planetary system.
Otherwise I think the mod is superb even without adding anything else, I’d give it an “A”, nice work!