I would dismount scope and rings and see if the holes in the receiver are drilled and tapped off center. R700's are notorious for this. If this checks out, then I would start the deep dive into rings. Since I have no idea if "Talley scope rings" are a quality set of rings, the problem may be there...but, with that much windage adjustment, I would bet it's the receiver. You can true this up at your own expense, possibly going to a pic rail and truing the rail up by oversizing the holes in the rail.
Take some pictures if you can.