Koehler's Bull (aka: Sorrells' Bull) was actually out of Bolio's sister (Daisy was Zeke/Goldie) bred back to Zeke, making Bull a 3/4 Klaus' Zeke bred dog.
I never saw the dog, but I heard he was cold. Still, he was an impressive physical specimen and a 3/4 Zeke dog. When I spoke to him, Pat Patrick did not even know that it was from Klaus' (Hernandez') Ch Zeke 4xW that Bolio got his head-fighting ability, as many rated Bolio's daddy Zeke as the finest head dog of his day.
Therefore, even though he was cold, I would say that Koehler's Bull would be an excellent stud dog to use, and would likely be a high-percentage producer (as his production record reflects). In fact, there were two Grand Champions off of Bull bred to Carver/Corvino-type bitches, that were behind Sorrells' foundation dogs.
Jack