It's billed as a "Campaign Option" that you can supposedly drop into another campaign setting. Chimpman already has a topic about using Ghostwalk in Mystara and there are several other topics about using Ghostwalk with other settings. I'm trying to go the other way and find things that can be dropped into Ghostwalk to expand the detail there.
Havard has spoken about connections between Classic D&D stuff/Mystara and Ghostwalk a few times, as Ghostwalk has Orcus in it as one of the local gods. So I know that there might be some Classic D&D adventures that could be modified to work on the island that Orcus cultists took over in the Ghostwalk campaign. But I was looking at the GAZ Series recently, as some of them are going onto Print on Demand on DMs Guild. I realised that we are coming to an era where I don't have to deprive Classic D&D fans/Mystara fans of a GAZ product in order to get one. (Or sell a kidney to afford one.)

LIST OF GAZ SERIES BOOKS:
- GAZ1 The Grand Duchy of Karameikos
- GAZ2 The Emirates of Ylaruam
- GAZ3 The Principalities of Glantri
- GAZ4 The Kingdom of Ierendi
- GAZ5 The Elves of Alfheim
- GAZ6 The Dwarves of Rockhome
- GAZ7 The Northern Reaches
- GAZ8 The Five Shires
- GAZ9 The Minrothad Guilds
- GAZ10 The Orcs of Thar
- GAZ11 The Republic of Darokin
- GAZ12 The Golden Khan of Ethengar
- GAZ13 The Shadow Elves
- GAZ14 The Atruaghin Clans
I need to flesh out the following Ghostwalk countries
LIST OF GHOSTWALK COUNTRIES:
- BAZAREEN: A rigid gynarchy ruled by mighty sorcerer nobles. 99% human population.
- HIKRIAN PENINSULA: The area around the City of Manifest is a forested area of coastline. There are three small islands with fishing folk off of the coast and two small towns. (Population not stated)
- SALKIRIA: A monarchy. 92% human population, 7 percent halfling population.
- SURA-KHIRI: A monarchy. 99% elven population.
- COIL (Demiplane): A Yuan-ti demiplane with multiple connections to Sura-Khiri.
- TEREPPEK: A pedocracy ruled by a Council of Learned Bureaucrats with a dwarven monarchy in the Thanaurmar Hills. 98% human population, 1 percent dwarven population
- THURKASIA: A republic with a token monarchy. 95% human population, 2% gnome population, 2% dwarven population.
- XAPHAN: A theocracy ruled by a Council of Vampires. Formerly known as Inuitea before cultists of Orcus seized power. 4% human population, 95% undead population.
I'm not sure there is anything like Xaphan in the GAZ Series, but I would actually be more interested in working on the history of the doomed island nation of Inuitea. There are some Inuitean refugees who managed to escape the islands, and some still escape to this day. I need to build up a damaged island monarchy with merchants and fishing fleets.
Does anyone have any ideas? Would any of these GAZ books be useful to me?
Are there any GAZ books that would be a poor fit that you would suggest I avoid?