Hello Stephen,
You have done a really nice job here with a difficult pose. Excellent! However, there is one thing which really sticks out like a sore thumb: the ankles are as big around as his upper thighs!
Honestly, the lower legs look like they come from a completely different figure with different proportions - which they apparently did!
The best solution would be to replace the lower legs entirely. The second, less drastic solution would be to carve the existing shins and ankles down to a more acceptable size. In no way should the ankles appear anywhere near the same size as the thighs. In fact, I would recommend fattening up the upper thighs as well. The upper legs usually taper in size from the top to their thinnest point just above the knees.
I hope you don't take this criticism the wrong way. I think this really is an excellent model! It is only this one minor anatomical point which, for me, lets it down visually.
Cheers!!
Mike