over the many years i have played with 11" rear drum brakes, i have used the drums from trucks, vans, and C bodies interchangeably, from about '66 or so, up into the '80's.
as long as they have the 4 1/2" bolt pattern, they fit, either as a complete assembly [backing plate included], or as just a replacement drum.
as stated, they come with or without ribs.
it will be interesting to see what rock sends.