Stupor Mundi was designed for Mongoose RuneQuest, so it needs some tweaks to use with BRP, but it is not difficult to do. The differences are mainly in magic, but since you are in the d100glorantha discussion group you already have access to my list of spells that makes the MRQCore/MRQCompanion spells compatible with BRP.
Compatibility with CoC
arkAges is just a matter of adding SAN. One of the adventures in fact involves dealing with Cultists of the Devil and a couple of monsters that could require a SAN roll.
If you want to look at a sample, the adventure "Hounds of Adranos" is free and available in the download section of this site.