[RichardJ]

You're over thinking this.
as long as the outside diameter of the hub is the same as the diameter of the hole in the drum, it is centered. The lugs just keep the wheel, hub and drum locked together.
If you look at aftermarket wheels, some are hub centric and some are lug centric. Hub centric uses the hub to locate the wheel and the lugs just hold it on. Same with your drum.
I've never seen a factory lug centric wheel and I would never imagine them doing it with a brake drum.