Bryan,
I am not aware of any online references that will answer all your questions about the rib-sides. I did look through the Rib Side Caboose book by Kehoe, and there really isn't a complete listing of all the various modifications. As you know, the Milwaukee Road was the Non-Standard Railroad of the World that tried all kinds of different ideas.
According to the Kehoe book, the transformation to an oil stove from coal (with the resulting modifications to the side) began in 1958. "By the mid-1960s, nearly all the coal stoves were gone: yet surprisingly, a few locally assigned rib-siders kept their coal stoves until they were retired."
The side modifications are really quite simple to add. Just some thin styrene with a couple of fittings, along with a mess of weathering to represent the oil spills. For the late-1960s, rib-siders with straight-frame trucks were more likely to be found on cabooses assigned to yards and on patrols, while those with drop-frame trucks were more likely to be used on mainline assignments.
Kehoe also states that the original paint scheme had disappeared by the late 1960s.
Bryan, what is your modeling plan in terms of location and operations? Sorry if you have shared this before, but I can't recall.
Hope this helps.
Best wishes, Dave