Well, the originals was modeled around someone who weighed 70kg(140 ish pounds) and 5'9"(175-180cm) if i recall correctly. So 5'10" and 155 pounds isn't really that "big" if you used regular size you would just have a bit more black showing on your legs / arms if you are taller and if you have a gut more space between the from and back plates.
A tip before buying is read a lot of build threads, look around the forum, check the references up top and look here http://www.whitearmor.net/fisd/Tutorials