MikeG said:
If we don't know about their gait, we don't know about their legs, hips, belly, shoulders, arms, hands etc.
Without knowing the attachment of the atlas to the skull, we can't know how it held its head. If we know that, we can make some scientific wild-donkey guesses (SWAGs) as to its gate. That said, evolution is just weird, and an upright organism with a knuckle-walking attachment of the atlas and skull isn't impossible (it's not ideal, but then again, neither are external testicles).
Given the material I've seen replicas of, I'm more or less okay with using, as a working hypothesis, an upright gate. It's a reasonable working hypothesis.
The rest? Pure speculation and mere opinion. I'm generally overly willing to accept, at least tentatively, some hypothesis, and even I'm not willing to venture an opinion here.
http://palaeo-electronica.org/content/2014/917-commentary-state-of-the-palaeoart
Here's a fun discussion of paleontological illustration, in a peer-reviewed journal (open-access; no paywall). It discusses the problems, as well as the benefits, of this facinating field. The importance of this field CANNOT be overstated--my path in life was, to the best I've been able to determine, set by paleo artists (animetronics, but still). An entire generation of my field has been inspired by
Jurassic Park. And it's a rigorous, lively field of study. Well worth the read if you're interested in how this sort of thing is really done.