Cypher-Finder?

Not unsurprisingly, a Pathfinder Classic conversion to the Cypher System would not be that hard at all. For the most part, the core Cypher System rulebook would be used, and you don't need many of the character classes in the base rules. At most, this book will be helpful for equipment and magic items.

The Bestiary will be the book to focus on, since you will be using this to rate monsters on a 1 to 10 difficulty curve, pulling out special attacks and defenses (and rating those in the system), and using it for inspiration. Most of the other books are skippable for a core game experience.

Godforsaken, being the Cypher System fantasy add-on book, will provide a significant boost with a few extra options. Check this and the core rulebook in the character creation tool and save it as a campaign. This will give you a few more options to explore. This book also provides suggestions for various character classes in a traditional D20 game and recommends the Cypher System foci to use when creating them. This section is an invaluable guide to building a character, and will tell you how to make a sorcerer feel and play differently from a wizard. This book also features a comprehensive list of monsters for inspiration.

I would love to see Paizo work with Monte Cook Games to deliver a Cypher System version of Pathfinder Classic, just like they did with the Savage Worlds conversion. With a new universal core Cypher rulebook, we could get a themed sourcebook suggesting how to build the Pathfinder Classic classes with Cypher, and maybe a bestiary, too. Combined with the classic Paizo art, this would be a must-buy for me, and a huge attention-getter for the system.

Until that happens, I can DIY this easily with my PDFs, and start playing today!