For something that old, you might need to check with a local salvage yard. Or do a search for a CB specific forum and see if the members can help you out with the parts issue. There is quite a dedicated following of the CB series.
Check e-bay I've bought plenty of parts off there to fix up the basket case GSXR I had. I did a quick search for your bike and found everything from rebuild manuals to clutch and speedocables even a front axle.