Don't know that worrying about the reasons is a productive time use but if your one of those individuals that has to know the story behind the story behind the story - good luck
I figured they (based on engineers and past experience) knew it would work in most cases and a bigger more expensive option could be sold in those areas where heat was a bigger issue. More money for the stock holders
Since you have a San Jose car I suggest you focus on the markings that would be found on a radiator that would typically be installed at San Jose rather than the long version of the engineering number. You referenced a number of examples that ere stamped with C7.... not something found on a Modine radiator
Sounds like you bought a Dearborn/NJ style radiator you'' need to find a new home for Good it was cheap.
So not sure what radiator you think was original to your car. Don't have any examples with C7ZE R's
Guess I would start with how your car was optioned and built.
Guess you have a Marti report and didn't find a build sheet.
Engine, Trans, Thermactor, AC would all play into (including option packages) what radiator you would have originally had. Guessing that you have no way of proving the picture you took years ago was indeed the original out of the car.
Here is how the top tank and the soldered on tag would have looked