I just wanted to add that even though the breeding would be a total outcross, that doesn't guarantee that the allergies wouldn't surface in the puppies.
Ghilly
If the litter's sire had bad allergies, and some of the litter has them as well, as much as you might like to breed your girl I wouldn't, since it seems there's a very good chance that the puppies could also be affected. Even though your dog is asymtomatic, she still carries the gene for a weakened immune system. Not only would it be unfair to the people who ended up buying the puppies, speaking not only in terms of medical bills but also in terms of watching the dog they love suffer with the allergies, it would be unfair to the dogs themselves, since they would be the ones suffering with the allergies. I know it's not what you wanted to hear, but when it comes to creating new lives, we must be as realistic as possible and strive to do only what's best for the dogs in question.
Ghilly
You would get a better answer by contacting the national breed club for this dog. Every purebred dog recognized by the AKC has a national club, and a web page as well. They're the experts on these kinds of issues.