The first thing is to modify the majority of the arms so they aren't so 2 dimensional. I've already decided to give each Skarboy a sheild so as to easily differentiate them at a glance plus it helps reenforce the 4+ save. Each boy will have either a slugga or a chappa in his free hand, with the other item slung.
Now this nob got a new arm to be placed across his body, roman soldier style. I made a V-cut in the shoulder to get the correct angle.I'll fill the gap with green stuff and cover it with additional armor plates. Here's the back:
And the front: