Usually modern conservation work tries to avoid wet processing on old materials. If there are plenty of unimportant images to discard, you can test your refix, toning and washing process. But be prepared to see unpredictable hue shift in the image, as the reaction of the toner depends on the paper emulsion and how the image was developed first.
If all these sound too much work, you can make duplication prints (perhaps digitally) for display and keep the original in low humidity dark storage. If the humidity is kept low, a bit of residual fixer does not do as much harm.
Another option is Fuji AG Guard. It may not be sold in your area, but it is an excellent image protecting agent like polysulfide toners and gold toners.