Greg,
Sorry your question has been here so long without an answer -- or at least an opinion.
Mine is pretty much an opinion: Since the Good Health and Iron Mountain lines of cast iron were both made by Griswold as a "cheaper" line of iron to be sold in various retail stores, I would expect them both to be in the same display area -- and knowing retail stores (just as now) they will sell you any combination you want to buy. I really don't know if Good Health had lids of their own, but would suspect that they did, since Iron Mountain did. A lot of times, a skillet or oven Dutch Oven will have a matching lid that doesn't have a single mark on it -- making it quite difficult to determine what lid goes with what and/or if the skillet manufacturer made a lid for the skillet or oven.
I wish there was more information about the Good Health and Iron Mountain iron. I have an Iron Mountain skillet and would like more items like it, plus more information about the other possibilities in that line.
If you can, please post a picture of the Iron Mountain lid. I've never seen one.
Jerry W.