I'm not going to say you have the wrong cylinders or if they are made wrong as it's possible that that is all that is available.
However, you could grind a small amount off of each side of the bracket to give some more clearance.
I worked in a brake shop in the early 60's. One of the "technicians" would use an air chisel and cut the tabs off to rebuild the cylinders. When I asked him about what he was doing he stated that it was easier than removing the cylinder and besides "Ford's never used them and they built millions of cars and he never saw a problem with them". It may not be the best way but it worked for him.
Fred
