I think you'll find that the mandalorian blueprints are quite off on almost everything. They're a great place to start but, by no means screen accurate.
I think you'll find that your best bet is to go through the reference cd and there are some really good straight on shots of the chest armor that you can use to almost trace for the shape.
Adjust the size to your own body type of course but, I think you'll have pretty good luck with that method.
Jer