Where can I find a female Bullmastiff for breeding

She should contact the Orthopedic Foundation for Animals (offa.org) first and get his hips and elbows x-rayed for dysplasia, as well as his thyroid levels checked before breeding him. If he doesn't pass, he should be neutered immediately.

Sorry, happyever, but purebred just means he's only one breed and champion blood lines could indicate that anywhere from one dog in his ancestry was a champion to several. Has he ever been shown? Showing a dog to his championship or at least exhibiting him and getting feedback from other breeders is a better indication that he's worthy of passing on his genes than his pedigree. It's a little like saying I have royalty in my family tree.. it doesn't indicate that I'm royalty, just that I'm descended from it. And I agree with iiartisanii, he should be tested for genetic diseases and defects like hip and elbow dysplasia, hereditary eye defects and his thyroid before she even considers breeding him. Imagine breeding a litter of puppies that will live their lives in pain because proper testing wasn't done.