But over the years to illustrate the stratification of Mi Go hives I've used Kuntz & Ward's Advanced Dungeons & Dragons Deities & Demigods Mi Go entry from the Cthulhu's Mythos section. I had specifically avoided Chaosium's Call of Cthulhu rpg because of giving the Mi Go an upgrade later on in the campaign. Different Mi Go hives adapt in different ways to various conditions that these things find themselves in. Realms of Crawling Chaos for Labyrinth Lord has a slightly different variant of the Mi Go. But all of these modern take on the Mi Go derive from the D20 Call of Cthulhu released back in 2002. So the Mi Go are now available under the OGL which is where 90% of the OSR content comes from anyway.
On the recommendation of a friend I busted out the Teratic Tome by Rafael Chandler. There are quite a few horrors in this bad boy that fit the line of campaign that I'm writing here Rafael Chandler's universe is chilling place with flashes of light coming from those willing to stand against the onslaught of darkness.
I've got to work out a bit more of the mythologies & backdrops with this campaign but its coming together quite nicely. The balance between the modern OSR vs the old school material meshes very well. The question in my mind do the PC's have a chance? Honestly I don't know yet as it stands.
So this campaign is in no way shape or form ready for prime time at the table top level, yet. Part of the process for me is to keep refining adventures,campaign elements,etc. not to write scripts or stories but adventures that work. Its all a part of the process for me as a dungeon master.