Yes, if you use the Pirate Jack or DoctorDiff kits you have 73+ style rotors that are machined and have the 5x4" pattern added, and they either need to be sourced from them or machined locally. Given how little most folks drive these cars, they may never need to replace them. I put 70k miles on the 11.75" rotors on my Challenger, they probably couldn't be turned again at this point but they had no issues going through two sets of pads. And I doubt many on here will put 70k on their cars anytime soon.
There is more than one hub bore diameter for the SBP wheels. I thought it was drum vs. disk, but I could be wrong on that. There are definitely SBP factory wheels out there that will not fit the Pirate Jack or DoctorDiff 73+ rotors machined with the 5x4" pattern even though the hub is turned down from the factory diameter, it's right in the disclaimers from Pirate Jack. There are also ones that apparently fit, otherwise why bother with turning down the hubs?
And yes, the 73+ spindles and rotors do increase the track width. So if you don't have ample clearance with your current sbp wheels/tires then that kit may not work without new wheels. Depends on your wheels and tires, I'm sure some will work and others won't.
Wilwood disks also have a large diameter hub (even larger than the BBP 73+ disk hubs), so, factory SBP wheels are a no go with the Wilwood kit too. They also use 1/2" wheel studs.
Totally agree with the OP on the drum spindle thing, at least with the '67-'72 spindles. The 9" spindles do have failures. They were discontinued by the factory early. The larger wheel bearings on the 73+ spindles are better (both drum and disk). And what's "rare" about the disk spindles? The '73+ disk spindles are reproduced, you can buy them anywhere. None of the drum spindles are reproduced, and how many have been tossed at this point?
