The notches provide clearance for the flange bolts, I have BORA 1" spacers and they definitely needed those cut outs to fit on the front end.
edit... scraped this picture from another thread to illustrate.
@waynegro, take a look at the two spacers on the right in this photo. Do at least two of yours have the notches in the bore? If not, they don’t fit a 100 front end.