The only factory 5x4" disk set up used the 4 piston calipers and small ball joint UCA's (67-72).
If you already have the large ball joint control arms (73+), then your only truly factory option for SBP would be the 73+ 10" drums, which were 5x4".
But, DoctorDiff does sell the converted 73+ rotors that have the SBP instead of the BBP. Basically, it's the normal 73+ disks that would have been 5x4.5" but with the rotor re-drilled for 5x4".
The issue that comes up with the 5x4" conversion rotors is that the hub register is larger than the original SBP hubs. Which means that factory small bolt pattern wheels will not usually fit with the converted later rotors, even if the bolt pattern matches because the hub bore of the original SBP wheels is too small. The same is tru for the dual bolt pattern Wilwood kit, that one has an even larger hub register (3.06") so NONE of the factory wheels fit, early, late or even reproduction. The wilwood kit is aftermarket wheels only now.
Call DoctorDiff, he can explain the options on what he carries. But I know he's mentioned that he can replicate the MBM kit, which is the 73+ disks with the 5x4" pattern added.