I believe Stealth Arms is getting out of direct sales and going through vendors and retailers now. I'm not positive on this, but from what I can tell by doing a google search, it seems like they are only a couple years old and are getting more involved with online vendors to sell their kits. (i.e. sportsmansguide.com, slickguns.com, calguns.net etc.).
Also, I don't think they sell a jig kit for the 80% 1911 frames, because there is a little more machining involved than drilling holes. I think the Slide Rails need to be machined into the 1911 80% frames. That would take a bit more skill by a machinist. Also, you would need the slide you would be using to get the "perfect" fit when fashioning the slide rails.
I've personally seen and handled the 80% AR lowers and the 80% 1911 frames, and I'd have to say they are very impressive in the quality department. Very high quality aluminum, light weight, and the machining is held to Mil-Spec. Very few (if any) sharp edges and burrs to contend with like other cheaply made 80% lowers and frames. Keep an eye out for this company in the coming months. Big strides in product and development are in the very near future. Very high quality for the price. They will make some waves in the market very soon!
Hope that helps!