Another product made especially for cleaning vintage linens is Restoration.
I've not used it for flood water stains, though. Years ago I did clean flood stained clothes for an aunt and uncle. I remember I had to clean multiple times with a variety of laundry stain remover products and laundry soaps. People who have never been in a flood think it's just water, which it isn't. It's thick and muddy, like brown pea soup, and it has sewage in it. Lots of pathogens, not healthy at all. It stains the walls inside and outside of the house, everything it touches.
Good luck.