I believe it was possible to separate them. People would buy after market billet mounts like Gorilla Billet . Also Grafton, precision billet and Magura made mounts. So depending on your model, you'll have to find the correct ones. There was a discussion on these on shifter pod mounts | Retrobike
I've hacksawed and/or dremeled several sets of the brake levers free of the pod mounts. You can get them to turn out looking pretty nice if you take your time. You don't end up with "show quality" levers, but for a rider they will do just fine. The ones I've done look just like regular 2-finger brake levers unless you look very closely.