I bought one a year ago from them. The BATF says if you want to use the original tube it must be altered so that a full auto bolt can never be put in the receiver. The other thing some builders are doing is center grinding the bold to reduce it's diameter (it won't turn on a lathe, tears up the tooling) and then building the gun up in a smaller receiver tube. You will also need to change the way the trigger group works. It needs to have a disconnector and a sear in order to be approved by the BATF. In the original design the trigger engages the bolt directly.
Look at the Sten bolt over at http://www.semiautosten.com/ to get an idea of how a bolt and striker rig work. There is a guy in KC, MO working on a 2 piece bolt for the 26, he's already built one for the UZI.
I've pretty much given up on mine. I'm going to use the barrel and mag well to build a a shortened AK style pistol, like the BISON, http://pookieweb.dyndns.org:61129/bizon/bizon.htm
Let use know how your project develops is you build .
Aaron