I was thinking Masks of Nyarlothotep could be a fun one that keeps the characters all over Golarion... Fungi of Yuggoth possibly as well.
I have long considered trying to do something like this. Masks and Fungi would be great as would Beyond the mountains of madness and Tatters of the King. Several of their standalone scenarios should also transfer quite easily. A lot of the scenarios from Trail of Cthulhu would also be excellent, heck almost the entire adventure book Shadows over filmland could just as easily be placed in Ustalav since the setting known as the backlot Gothic basically is an undefinable generic clichè Gothic setting. Also, most of the Trail of Cthulhu adventures are more pulpy than the classic Chaosium stuff, meshing better with Golarion, which is a pretty pulpy setting in itself. Maybe I'll try something like this for my next Campaign.
Check out Yog-Sothoth.com for a pile of d20 CoC stuff and a bit of Dark Ages CoC
Check out Yog-Sothoth.com for a pile of d20 CoC stuff and a bit of Dark Ages CoC
+1, yog-sothoth.com is my favorite site for Cthulhu goodness.