Bought some worsted flannel from Harrisons Burley in the past month and made some pants as follow. The sand one is around 13-14oz and it looks similar to NMWA in term of color...The rust one is over 14oz, particularly nice for pants.
Not particularly good, but acceptable (presume it is cheap). Shoulders and sleeves may need further adjustment.
Simply removing the shoulder pad won't help you to achieve the look you want. This has been explained many times here.