What are your views/opinions/dislikes of AR kits? This particular one would be unregistered as the lower receiver is “manufactured” by you.
Comes with a jig too.
Of course, you can purchase their “kit” with upper included for around $700.
Check out the video at the link on the actual rebuild. All one needs is a drill press, and an X-Y cross vice, relatively inexpensive additions to any shop.