Well! It seems to be working! 2 nights, no yeowling. She still wriggles a bit when I pet her near my feet, but she doesn't stiffen when I pick her up to cuddle her. I gave her about 1cc last night. She's not terribly cuddly, but she is quieter, and accepts cuddles & doesn't want down right away, either.
So, Black Cohosh for a cat that needs to be fixed & is in pain after a certain amount of time, seems to be a good thing.