Comment on WordPress SEO Categories by SEO Dave.
If your permalinks settings use this custom format /%postname%/ (Looks like yours does) you can switch WordPress Pages to WordPress Posts with no need to setup any 301 redirects.
Important if the Page has URL
It still has that URL after changing to a Post.
If you did have a permalinks settings with say the date or a category name it would require some 301 redirects to pass SEO benefit.
Looks like all you’d have to do is switch Pages to Posts and set a category, easy to do.
I use the WordPress Post Type Switcher Plugin https://wordpress.org/plugins/post-type-switcher/ for switching. Never had to switch hundreds at a time mind you, I’ve switched handfuls of Pages to Posts at a time which doesn’t take long.
I’d probably do them in batches starting with the ones with most traffic so they get the links from your widgets and category archives and as you’ve not set the Stallion keyphrases set some of them as well.