Here is something similar to what I used for my soft bags:
link. They are universal, and all you need are two attach points, on the side. I had a '79 K, and I used the shock's upper bolt, and another at the back side, to attach the brackets.
There are a lot of bags out there, but if you want traditional, go with the fake leather types, as they won't mildew, or be damaged by rain, as leather will. There are a number of sellers, such as
Willie & Max, and
Leatherup.com. I bought a set from Willie & Max, but they were spendy. The Leatherup models were comparable, at a much lower cost.
I toured, two-up, on my Honda. We found that the plastic saddlebags tended to hang down too close to the pipes with the standard zip-off, OEM mounting system. We used some web strap material (gym bag straps), from a fabric store, to make custom straps for over the seat, in an X-pattern. To keep the bags from flapping in the wind, we bought some caribiners, to attach the lower loops on the bags, to the support brackets. This kept the bags loose enough to move around for the passenger, but secure enough not to flip around when riding. They were easy to remove, for carrying into our motel at night, without using removable liners. Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII