I have the exact same rifle. Mines has a hs precision stock that used to have a blind mag. The only suggestion I have is check cdi precision. They did the I letting for free, which will easily save you a hundred or so. The woman on the phone, I believe the wife of the owner, was a very lovely person and very helpful. It was easy and they inletted mine for free even though it was completely blind.
Im not sure if the stocks u are considering require it or not. But if it does require inletting, then it can save u some moneys.
Aside from that if you're only getting one mag, get a 5 rounder.