I don't have a motor, nor do I have a lead on one, sorry.
Just a heads up, the cataract rangers can be pretty strict about motor use, so make sure to cover all your bases before your launch. You may already know this, but not everyone does.
The three requirements for motorized rafts; placards that display the state issued number (3" or 4" tall), a valid and current registration, and an readily accessible fire extinguisher.
Here's the catch. If you borrow a motor, the motor itself isn't registered, it's typically the vessel (hull, frame or transom). So if you show up with a registration paperwork for a 16' Avon and the motor is mounted on a 14' Cataraft, this could pose a problem. It's kinda like borrowing your buddy's license plates. If you are nice to the ranger at the ramp, you might slide right by, hard to say.
What some folks do is rent a raft with registered motor, I believe NavTec in Moab once offered this service. It's gonna add to the group cost, and is not ideal, but the upside is you are fully legit, and hopefully you will be renting a good quality motor with proper routine maintanance.
I've seen motorized trips get shut down without jumping through the hoops and it's a bummer. Sounds like there is current past the Dirty Devil, but "current" is a relative term.
Have a great trip and best of luck.