Well you are on the right track, measuring the width, simply because it is much easier to scale. Now the next part is much easier if you have someone willing to help you. Take that width scale and use a ruler or tape measure to judge where that width would fall on your shoulders. If it seems too wide or narrow, adjust accordingly. Now the nice thing about the V4 torso is, the widest point is actually the soft armor. You can build the "hard" armor to fit your body, if you need to adjust more than one measurement (width, height, depth), then adjust the soft armor accordingly to fall properly on your shoulders. Long story short: use the smallest dimension that will fit your body. When I say that, if 1 of 3 measurements will fit you comfortably, and the other 2 are a little big, it's going to be much easier than trying to get all 3 measurements perfect. Help a little more?
-Matt
-Matt