I believe he allready has factory Kelsey Hayes 4 piston setup.
Don't the SSBC and Scarebird have the same 11" diamter rotors as stock KH 4 piston setup? I'm pretty sure they do, so I don't consider them much of an upgrade from factory.
The Willwood would be interesting to see if you can fit a 12" rotor with inproved calipers on the same hub that fits SBP.
I think some of the Willwood Mopar hubs are setup to take Small and Big bolt pattern. Don't know if this same hub can be used for 12" or bigger disk setups.