Yes, I did use a Fluidyne Shelby replacement 3 core in the CCX.
Howe or Griffin should be able to handle the exact drop in. John Montgomery, now a Unique 289 owner, used one from Griffin with a great shrouded fan attached. Drop him a line for first hand experience......
There is also a guy in Indiana that makes great taylor made units PRC. Mickmate has his contact information above. These are top notch and you will speak to the guy making it versus the corporate run around on a custom unit.
Jeff