Forgotten Realms seems pretty inappropriate for WFRP, IMO -- at least not without some major modification.
WFRP is the ultimate 'grim-n-gritty', 'life is cruel', 'magic-is-dangerous' system. The WFRP mechanics and the Old World are made for each other. In contrast, FR is a 'high/safe magic' setting, where every bartender owns a +2 cudgel, and people live in ostensibly 'medieval' societies, but all hold 20th/21st century western liberal values.
Wilderlands might work -- it certainly is *not* a 'politically correct' setting. Some changes would be necessary, but the setting is flexible enough to be modified in any number of different ways.