Graphic Design/Font type
There is a kind of font where the upper case letters are merely larger versions of the lower case. One example of this is Unifur. Such fonts being very rare, however--perhaps one in two thousand--they are extremely hard to find. The situation is made worse because this kind of font face has, apparently no classification. For instance, even were I to go directly to a standard category such as "sans-serif" I still would have to poll through perhaps thousands of sans-serif fonts faces to find (maybe) one of the kind I require--and so which likely would not suit my needs.
Can you suggest any means by which I could narrow down my selection so I don't have to spend perhaps completely unfruitful days searching for a suitable font?
You're in luck on a couple of different levels.
First of all, there is a classification. Search for headline fonts. I am assuming you don't mean small cap fonts, but they would also essentially fit the description you gave.
Second, you can replicate the effect you describe in virtually any publishing application. For small caps, there is usually a button you can press to create the effect instantly. For a headline effect, you may need to create it manually, but I wouldn't imagine you'd be using a font like that for a large amount of text, so it may be worthwhile.
Best of luck,