Since this trooper is seen on screen he is eligible to become a Legion costume. But being that these troopers are from the Special Edition, the armor is different from the original TD armor. The backpack is also different.
The armor is based off of the Return of the Jedi armor and helmet. Do you have ROTJ specific armor? You could modify an existing set appropriately or get a set of specific armor. There are two makers that I know of who this set. You might have to do some research for the SE backpack.
I don't know of anyone who has made these specific TD's but they certainly are unique in their own right. Contact our Detachment Leader "Dirty Boy" for more guidance and coming up with a CRL.
Good luck!