I think out of the four suggestions here, it has to be the rending claws - the crushers look way too big and unwieldy, and both of the guns are 1) too obviously Tyranid and 2) along with the overall pose, give the monster a kind of cowboy gunslinger look?
I mean, that is, unless you're going to put a Stetson on him, in which case it MUST be the deathspitters.
Since you can see all the thing's ribs etc, a skeletal arm might also be good? Something from the tomb kings or suchlike. Bone giant comes to mind, but I think he's too big, I'm not sure of the scale.
Dark Angels. The Rock. Lion El "Dwayne" Jonson. I can't be the first person to have thought of this.