Here are 2 photo's one with the early ampersand and one with the standard ampersand.
There are a few aftermarket target weights made, if you purchase an original, you would have to fit it to your frame or you could damage the finish mounting it.
I prefer shooting with the weight, it does make a difference. If you wish to purchase aftermarket the best one is made by Tim Bell, he is on GB.
IF you want to spend the extra money to get the original, I have a few spares.