As noted the 28 always came with Magnas and these usually are numbered to the gun. Targets could be ordered but very, very seldom were. Dealers would often install them at customer request. Targets are almost never numbered even when original.

The 27 came with Magnas until 1974 or 75 when S&W foolishly (IMO) decided to make them all full target options as standard. I say this because the 3.5" look ridiculous with the big hammer and stocks (again IMO and I apparently am the only person in the world who feels this way).