They're nice conversions and the paintjobs certainly make them look like they've been out of the game for a while.

But I have to agree with Mr. Giraffe here: that helmet looks a bit too jaunty like this. Might I suggest cutting off part of the skull and placing the helmet on like that? Then it would appear as if the skull is actually inside of the helmet.
Unless the problem has to do witht he fact that the skeletons are actually too large to actually fit inside the armour, because WA's offerings are on the whole slightly larger than those from Agema and Victrix. The slightly large noggin' on the left skeleton is probably proof of that.
What I can suggest is a bit more hands-on and fiddly, but might work: cut off the face of a skull, and carefully shave away the face of a helmeted head, then cut and fit (and cut and fit) until the skelly face fits inside the helmet. It'll take hours, but that way you can have a helmeted skeleton.
An other way might be sculpting a helmet on top of a skull. The shape is not too difficult, and you can add a plastic plume afterwards.
Hope that helps. The concept and execution are otherwise pretty spot on.