I saw on the web that the Stag 2T has a Samson rail. Troy and Samson = the same, so try to get either one of those. Call Walt at AEI, he's the guy to talk to regarding Stag stuff.
For the 3-point sling, I asked around some months ago and almost everybody told me to get a 2-pointer. It does the same as a 3-point but with less hassle. I have the Vtac on my first AR, but I plan to get a Blue force Vickers. Guys on CGN seem to find it the best.