If it helps, it's usually preferable to work with quads...at least, for Game Design (I.E. Computer games). I personally would keep to that theory when doing pep...those triangular bits are a pain, from what I've tried. Also, I've noticed, and someone else pointed it out, I think, that the chestplate could be a lot simpler without the aquila. I'd be more than happy to do the modeling to tweak it. I know a little bit of 3D work, from a few classes. For that matter, anybody looking to do more recent versions of the Space Marine armor (I.E. the non-beaky helmets and seperate knee and shin plates) can probably tweak the 3D models if you release them later on. I've recently started doing pep stuff, and it occurred to me that since Bondo and resin are used extensively in this kind of armoring, the 3D model
might not need to be as rounded, thus saving a few polygons, and making the final pep even simpler. This would probably require a bit more bondo work, but so long as it's not ridiculously simplified it shouldn't be a big deal. And in the end you can add whatever the heck you want to the chest. But these are only suggestions