I should also probably add a couple pointers about hanging large artwork on picture rails. Generally, the hooks on the back of your artwork that you use to hold cable or chord should be attached to the side rails. This is always stronger than the top rail where joints can brake and the entire picture (and mat and glass) can end up on the floor. I am using 1/4" loop hooks that are about a 1/2" long (into the wood).
People have also asked about how you minimize the hanging angle. You can't eliminate it totally but the higher up that you mount the chord or wire hooks on your frame, the lesser the angle will be on the wall. I am using hooks at about 3" from the top of the picture for this one and due to the weight and size, the angle is minimal. On smaller pictures, you can get as close as an inch from the top rail.