well lad first make sure it off good proven working stuff,thats the main thing.% is harder to say because they can be different litter by litter or pup by pup.i've two 3/8 5/8 sisters here,both good bitches but the bigger one is far slower than the smaller one.the smaller one catches more but to see her you wouldn't think it.the bloodlines is down to the dogs you know that the pups are off,just be sure that both parents are well proven singlehanded dogs and that they both have plenty of years work done.Don't buy any pup from young dogs that haven't proved themselves.Best of luck lad.