I would reccomend a Manx over 6 months old because the bowel problems associated with taillessness can first appear up to four months of age. A Manx, by the way, is a specific breed of cat with a certain body type. Many people just call tailless cats Manxes. If she is looking for just a tailless cat, which is due to a genetic mutation, check out this one in Ontario:
Siamese Manx
Tailless cats are relatively rare and should never be bred.
Lisa
Harry (tailless tabby/Maine Coon mix)
Egg (tailless Siamese/tabby mix)