I'm having trouble with CFrames. Could someone help?

I'm trying to get the head, at least while in first person, to have the exact same rotation at the camera, regardless of which way the Torso is positioned.

The following pieces of code I have tried out do not work. Could someone tell me why, and help me out with this problem?

char.Torso.Neck.C0 = ((CFrame.new(0,1.5,0)*(cam.CoordinateFrame-cam.CoordinateFrame.p)):inverse()*(char.Torso.CFrame-char.Torso.CFrame.p)):inverse()

char.Torso.Neck.C0 = CFrame.new(0, 1.5, 0) * CFrame.Angles(math.asin(camera.CoordinateFrame.lookVector.y), -math.asin(camera.CoordinateFrame.lookVector.x), 0)
    char.Torso.Neck.C1 = CFrame.new()