I'm not sure how old this guide is, but I believe our clone_items() method should do most, if not all of the steps included in that guide, implicitly.
I would try just grabbing your storymap object with:
story = source_gis.content.get("your_itemid")
and then trying to clone that across to your destination gis with:
dest_gis.content.clone_items([story])
That should clone the storymap and all of it's associated content, data, etc. with it. You can double check by accessing the item in your portal, or getting the cloned storymap object in your notebook and examining the properties.