Re: My humbucker has 56mm spacing...
For the part to be replaced the only thing that really matters is the spacing between the screw holes on the mounting tabs (or 'legs'), and the edge-to-edge width and edge-to-edge length of the top surface of the plastic bobbin (the plastic part holding the poles)..
Pole spacing doesn't make a replacement humbucker 'not fit' unless you are using a guitar with a bridge that isn't close to standard sized or unless we are talking fitment of humbucker 'covers' (like nickel, chrome, etc)..