My finished rifle looks exactly like your, with a slightly nicer KVAR fixed stock, but minus the slots cut into the Saiga forearm.
Apparently, the trigger group was moved forward to improve balance, per the info stuff in the link at the bottom of this post.
I am just glad to find one with all the anti-second amendment talk about. The prices will go even higher as the scare tactics, real or perceived, will make it them more scarce, thus more costly!!!
If I can, I will try and get a Springfield in the near future, I miss my Supermatch model, but a standard M14 rifle will do!!!
This is a site showing my rifle, with the new slots cut in the forearm, etc...