From what I understand, Murray bought Noma and then folded. Briggs and Stratton ended up with Murray. And they do have some of the parts for those old Nomas. (belts and idlers, at least)
Problem is, most of those parts drawings are only on microfiche. I spent an hour or more searching for a pulley for one on the internet one day.
If you talk real nice to your Briggs dealer he may be willing to call his supplier and get a copy of the diagrams you need.