Studding my dog for pick of litter

Looking to stud as he has had several offers for adoption and high interest in future litters. Dipper is a 2 year old St,Bernard x Norwegian elk hound. He is approximately 200 lbs. This dog has an incredible endurance (especially for his massive size) and is able to keep up during joy rides on a quad, dirt bike or petal bike. He has a natural protective nature already chasing off a cougar and bobcat (presumably stocking small kids/poodle) wile in the woods. He is generally people friendly however has displayed a protective bark to new comers unless met with owner.