here is a tip for you two!
take a picture you wish from google with the front, back or side perspective from your model. for example the halo mark V.
for example this
then open it in any picture editor and scale the size to the reference of your hight.
for example the picture i choose has a size of 347x425 pixel. now take your hight, my is 187cm (convert this for yourself)
the picture you choosen have to be cut in the top and bottom, because you need the exact hight of the model, not the pixture.
then it looks like this
now you can scale the model down to your hight. you've got an model, which have the markV armor and your hight...
the rulertool gave you the chance to define the hight of any armor piece you need.
for example the torso
the hight in pixel is ~88 pixel... or 88cm for me. because iam 187cm and the model too...
this isnt the perfekt way but, this gave you the chance to get the nearest size you want...yesterday i pep the shoulder piece of the odst armor with this method and it works... its only a little to big (by the way, the first try without the scale method gives me a shoulder pice which only a baby can wear