I thought I read where the others said you CAN use the stock hubs. Nothing here about "can't" that I see.
In fact, if they're in good shape, I still feel the original Dana/Spicer "Ford" hubs are the best for your Bronco.
And nowadays, they're kind of retro-cool anyway. Got some old school street-cred under their belt. So to speak.
FYI, Ford, GM, Dodge all used the same model locking hub (lockouts) on some of their trucks over the years. All '66 to '79 (and even later as far as the aftermarket versions) Fords, both Early Bronco, full-size Bronco and 1/2 Ton trucks used the same parts with the plastic Red knob whether on the Dana 30 or the 44 front ends.
GM used the same one, but with alternately either a Blue or Mustard colored knob on all K5, K10 and even some K20 trucks from at least as far back as '67, and up to, in some cases, the '91 model year.
As for Dodge, many of their 1/2 ton trucks and Ramchargers used the same hubs too. Intermittently spaced with some oddballs, but they were in there.
So the same mechanism that is in yours, is compatible with your new disc brakes. All the kits I know utilize a Ford '76-'79 outer hub anyway. So you're good.
Paul