i just made this same mod, nice info, thanks bummer6Speaking from experience, you'll want to move pivot of the shoulder joint. I tried having it the way you're currently doing it, and it just doesn't look right. Here's a quick picture to show you what I mean.
View attachment 757586
The left picture is where the pivot is on your armor right now, the right picture is where it should be. If you look at Sylgian's build, he came to the same conclusion.