'73 Disc conversion, but keep 4" bolt pattern

Those who want disc brakes and retain the OEM small pattern setup and whatever wheels they have usually opt for either OEM K-H disc brakes or aftermarket disc brakes, like Scarebird for example.

I was looking at the Scarebird kits on line and have a possibly dumb question. What do the wheel studs mount to? Of the parts shown, there doesn't seem to be anything.
The studs are part of the drum in my '67 Dart.