
I would suggest the kc accredited /assured breeders list as your first point of contact and speak to some of the breeders on the list.
a westie to show is a big commitment as they need to be hand stripped and this really is an art in itself. Also be aware that westies are very popular amongst the backyard/puppy farm breeders so research is essential.
Also contact the westie breed clubs as they should be able to point you in the right direction and will almost certainly have a puppy register.