Try the Carradice Classic saddlebag rack. It's a copy of the Karrimor Uplift, which was a copy of the Tonard rack. I've used the Karrimor for fifty-five years, they are quite reliable. So far as I can tell the Carradice is a bit more solid than the Karrimor. You will need a saddle with built-in bag loops.
If you want the bag an inch or two or three lower than the original position it is not hard to modify these.