Hey Jason,
A little input:
As the rebuilt radiator came directly out of my 145, prior to the car going to the builder, I know it's fine.
Additionally, the fan clutch is new - NO problem there! :-)
DON'T replace these known good parts, ie fan clutch or radiator.
It has to be another issue. Guage voltage?
Food for thought: I had a B20 rebuilt about 8 years ago. When I pulled the head off a couple of years later (fancy head went on), it was apparent that the head gasket was covering 1/2 of the water ports - Hmmmmmmmmm I thought. I didn't put energy into figuring out how the heck it ended up that way. But, that could have been an answer to my minor overheating issue. When I installed the new head, I made sure the holes were not partially covered by the gasket (course not - lined right up!). Again, I pondered, for just a moment, about the parially covered holes I had found - I let it go, focusing more on the current job. I never had a over heating concern after that. Then, a few years later, I put a hole in the radiator and had to have one rebuilt. That's the one you have now.
Now, I'm certainly NOT suggesting you remove your head! In fact, I've only found a similar issue one other time. But, in this other case, the water jacket blockage was due more to the many bottles of stop leak that had been poured into the radiator. The car had blown a head gasket due to the stop leak issue. H2O ports were CAKED with stop leak. Cleaned out the gunk, replaced the head gasket and radiator....never had a problem after that.
In summary, your overheating issue (if it is that, referring to possibility of voltage issue) is due to something other than your radiator or fan. Those are good.
Cheers! :-)
D