I am going to bring up something here about the original Sulaco model, particulary as much of the reference shots we see on the net are of the model later on when it was at Bob Burns place (I think after it was resprayed back to blue after being repainted for use on Alien 3).
You are doing such a superb job of this build, it would be bad of me to not bring up the following info....it was really just something I noticed when I was working on the Sulaco Blueprints. That way if I bring it up you can stick with what Jan has done (which looks great) or go the SA route.
A couple of the reference shots show a fin next to to top cooling tower as you can see below. This is on the papercraft model.
The fin I believe was actually originally attached on the side of the original model toward the back of the ship. I'm thinking it must have been knocked off at some point and probably just put on top of the model by Bob so as to try to not lose it.
That's all I got....
Best regards and well done so far on your model.
-SJ
EDIT: Just to point out that of course Pat McClung mainly built the original model; was writing on the pics from memory without looking at reference and wrote on the pic Rob Skotak.