5'9 and 130lbs i think it's very perfect. and armor building-wise i think anyone can pull it off bro, with FISD and us by your side you don't have to be afraid of anything.
I built my first helmet, VT, which is basically the same thing as ATA and it wasn't tough to build at all. And my ATA build was SO much more easier since it has all the trimlines and tells you where to trim, cut, etc.
if you go with ATA, you won't be disappointed. It's a GREAT armor.