Ok, I'm gonna put on my HARDCORE 501st minute detail costuming helmet for a minute here and give you some ideas:
I'd go with a modified TVC Bespin Luke belt, cutting the holster off and mounting on the opposite side of the belt. Or an imperial officer belt. You'd probably have to cut out the plastic kama/tunic from below the belt line. That belt buckle is definitely modeled after Imperial styles. Han's is often more hexagonal. and then add an X-wing pilot holster. As for the pants Bultar swan would work well. For the turtle neck, neck, I'd chop a Jes Gistang neck and add it to the top of any plain black shirted female tip. Possibly the bultar swant top, although those joints are nearly white. all stormies have a turtle neck-like neck and looking at the fem trooper's it'd work nicely. Just paint the surface above the black turtle neck fleshtone. For the head I'd retool the best Leia head to date, that being the most current Hoth Leia iteration. And splice the cina-buns from an ANH leia onto it. The gloves are definitely from the same Hoth Leia. You could even work in the Agent Helix bare wrists with them. Or just use those arms entirely. However the Hoth Leia gloves are very well detailed and look like the "leather" ones in this image. The Bultar Swan glows are not nearly as nicely detailed and are a bit big for Leia. Leia would probably have a matching blaster to Luke's and that style can be found in the Luke Skywalker and Deena Shan comic pack (in rebel armor). Keep in mind that Leia is pretty tiny. While her action figures are a bit too small, she's not much taller in the films. So keeping her proportions right will be key.
Alternate legs to use: Marris Brood (I may steal this idea for an updated leia!), The Dark Woman (upper thighs), Jarael (upper thighs). Then I'd add Joe legs for the knees to the feet for some articulation. With a dremel and some good super glue you could even create swivel or ball joints.
I'm excited to see your process on this! Good luck!
