It’s not weird. Those 73+ spindles will fit any of those cars, and more actually. The disk kit you listed is only for the original 70-72 B/E spindles, which are not reproduced.
So, if you don’t already have spindles, your best bet is to use the 73+ spindles and a different brake kit that is compatible with the 73+ disk spindles that are reproduced. You could even just get an entire 73+ disk brake kit, using factory replacement parts, from DoctorDiff. Cass @DoctorDiff has all of those parts and can sell you an entire kit, which you can then get parts for any any parts store.
Or pick a different a Wilwood kit, one that uses the 73+ reproduction spindles.