I'd visit and spend time with some. She'll know fairly quickly if they bother her. Fosteing is a good idea too. That way you are not committed to keeping the dog if she gets sick. I have tons of allergies (7 1/2 pages single spaced!) but not to dogs. I have a dalmatian, 2 greys and a Galgo. My dal sheds heavily (as all mine have), my greys are mild...but they DO shed, my Galgo doesn't seem to shed at all or very, very little. The greys seem to affect the allergy sufferers that visit my house much less than my Dal.
Good luck. Hope it works out for you.