Doug,
I thought that my fan (C8OE-B) and clutch (C8ZX-A) assembly were fine. The clutch provided some resistance, but I didn't know how to measure it. The fan spun when the engine was running and it briefly (very briefly) continued to spin when the engine was shut down. It seemed fine to me, yet, according to the temp gauge in the dash, the engine would run hot.
As an experiment, I replaced the C8OE-B & C8ZX-A fan and clutch assembly with a fan (C9ZE-E) and clutch (C9ZE-B) assembly that I pulled out of a '69 Torino Cobra. My first finding was that the C9ZE-B clutch had slightly more rotational resistance than the C8ZX-A clutch. The C9ZE-E fan looked almost identical to the C8OE-B fan, as far as blade count, design, and pitch. My next and most important finding was that my engine ran cooler, as measured by the same temperature gauge.
Since I couldn't find someone who could objectively test my fan clutch, and I have a replacement that provides better cooling, I can take my time deciding if I want to buy another C8ZX-A clutch or have mine rebuilt.
Unless you find someone who can objectively test your C7ZX fan clutch against its manufacture specs, I'd recommend you try a similar test before you purchase a new clutch, have yours rebuilt, or move on to changing other cooling influencing components.
Steve