That would be a good thing to do - use Model Sheets. I'm not sure if you can still find it but a long time back Marvel released the guide to the Marvel Universe (or something like that), where they had turn arounds of every character. You can sometimes find these floating on the net also. 

Thing is...ooooo....thing is, I think it's the torso more than the legs themselves that are throwing me off when I look at him.  Ben's fairly wide and his torso is actually the largest part of him but in your model it looks more like the legs/thighs are and I think that's because the torso is lacking the mass my brain is expecting.  It's hard to give you more than that without images to back it up but take a look at  John Buscema's version of him or his brother Sal's version. That's the thing about the Thing (see what I did there?) everyone has their own take on him. The one constant though is his width, even in the terrible first film and the two recent ones, he was fairly wide, so I think that's the one constant.

Still, have a look at him if you haven't yet and see what you think. It could be my own artistic taste is trying to impose itself here and I wouldn't want that.