Ovesized WGSD considered to be an industrial waste, exactly big ones are prone to develop HD through size acceleration via breeding big in size individuals. Also, larger WGSDs are doing not so good in Schutzhund or Agility as their smaller compatriots, the experts often disqualify them at the shows. So, if you are talking about sizy GSD - you better look at Easten German Shephers Dog photographs in the catalogue of GSD types, they are larger and more agressive. We even joked in times of cold war, that WGSDs were bred for sports and EGSDs were bred for guarding Berlin wall. My bitch EGSD from Austria weighs 46 kg, 74 cm to her shoulder blades, far too oversized and was disqualified for that. She is slim, because she runs a lot, you can count her ribs. She is super working dog, especially with tracking, found a lot but she is pretty agressive, what is controllable, because she is very obedient, obedience is in her blood. Ideally, you must come to European show to find the desired breeder, but if you cannot, try to visit one in US. All GSDs in Germany are checked for intelligence, those who didn't try in Schutzhund or Agility are not allowed to breed. The story is different in US, nobody trusts anybody, some people prefer to sheep their puppies straight from German kennels in Germany.
But, maybe you are talking about King Shepherd Dogs? If you haven't, read about them in Wikipedia, the breeders are not so far, they are in Canada. I don't think much about these KSDs, they weren't tested anywhere in intellectual places yet, and brainless GSD is not a dog for me.