[thorvald]

For someone that is rather enterprising you could try this for a metal body, assuming they are 1:1 exact for size (anyone with a real lower could simply stick your KJ upper on it and see if it matches up).

1. Purchase an 80% lower receiver from Dlask arms. It's not a firearm yet so anyone can purchase it. Only $220 CDN so its still cheaper than most metal bodies.
2. Remove all parts from the plastic body.
3. Use plastic body as a drilling template for the 80% lower.
4. Install all parts onto the now completed lower.

If you have access to a milling machine, you could purchase the billet lower for $45 CDN from Dlask and finish those to match the KJ lower.

Project for someone? ;-) Just be careful you don't finish it to work in a real AR... then you have 30 days to ...