The proportion is much better the way you have it now. I think the next thing you can really improve on is to tweak the pose so that it's even more dynamic and convincing than where you have it now. I'm sure you're already on top of this, but something I noticed is that there seem to be a bigger twist on the body when comparing the render to your current sculpt. While the hips are facing more towards the left, the torso is facing a little closer to the center with each vertebrate up, with the head ultimately facing almost dead center, making for a really nice twist to the spine. Also notice on the render that while the left shoulder is slightly above the right, the left hip is actually lower and falls back behind the right hip, and the left knee is even much lower and behind the right knee. This makes for a really nice and natural stance which I think can really improve your sculpture even further.
Would love to know if this will be available to the public some day, it's a really nice sculpt in a very nice and big scale, I think it'll look good in anyone's Alien collection!