Thanks for links, that german forum model looks like it has interchangeable left "arm", which is the difference between first and second movie, (ship was damaged by lava in Aliens), I was thinking about this option for a while.
As you can see, I'm using Giger's painting for the basic shape and adding details from here and there, there is a lack of some good shots of the studio model from some angles.
Also, what about the pilot's chamber, that clear dome is tricky... :/
First prototype layout ideas: