That is one of the more interesting set ups i have seen :-)
Two issue that I see ( may or may not be an issue for 501st approval, used to be a GML but that was years ago):
1. the white wrapping looks really long, normally it is about 2in long
2. The black strap attaching to the shoulder looks to be just 2in velcro...my worry, especially when trooping, is that it won't give you a lot of give when moving. I would recommend 1/2 inch elastic with velcro sewed to it in order to attached the shoulder to the chest. The elastic will provide give when you move and make it more comfortable over the long haul.
I would recommend wrapping with 2 in cloth and building an straps system with elastic attaching the chest and back and than to the shoulder....a "T" shape. When I am home from work I can post a picture of how i did mine if you like.