I've always heard about "C" (and perhaps you have as well) that "the only thing you can be sure is that a long isn't any smaller than a short.  (Which certainly doesn't narrow things down very much!)

However, I would have expected the same, that intsize would have been 8.  So I can fully see why you'd have questions regarding the veracity of the documentation for longsize.

By the way, I didn't mean to mislead you -- I'm not in any way an authority on the Config module.  I did just now look at the source for Config, but as it contained the results of running Configure, the values for the particular architecture were already hardcoded into it.  So I'd be asking the same questions you are.

Here's a thought:  trying downloading the tarball for Config and installing it manually.  Then you can look at the Configure script that comes with it, and make sure it's simply reporting the appropriate thing from the perspective of the "C" compiler.

Update:  I just now saw your response (below) to ambrus's suggestion, where you say you don't have direct access to the machine.  So you probably won't be able to inspect the sourcecode. :-(