120lbs mastiff/rednose pit mix 65lbs blue brindle pitt about to mate?

Bullmastiff/red nose chocolate brown 6yrs old blue brindle just turned 1 waiting for her second heat both house dogs great with children hince the reason I'm mating these two I'm hoping to get another king he is so big and powerful and has only shown aggression if someone fights around him serenity is a tail wagger very lovable king is a big dog and gettin old I really want to keep his bloodline in my family do u think I can get a jr