I'm just throwing an an idea out here, and I could be completely wrong - but rather than using a mod (with the downsides mentioned by CD Droege above), would it be possible to parse all the extra information from the pitboss savefile itself?
I'm pretty sure the game settings are not encrypted in anyway, but this is probably not the case for all other things. I guess it would be nice to have access to all the plots, not just the Score (GNP, Production, Military), and statistics. I doubt those are just in the file though. Most likely they're being calculated dynamically during the game.
But since the savefile contains information about the state of the map (how many units you have, what's built in your cities, their size, map tiles, and what tiles are being worked), then hypothetically it should be possible to calculate the value of each graph (though it would most likely take an enormous amount of figuring out to accomplish). That, and the fact, that most data in the file is probably encrypted to prevent tampering with it.