i don't suppose the replaced text is located in the text files (ie blurb0.txt, story.txt etc), in which it would be trivial to change the text back to what it is supposed to be.
regarding getting a new version of Civ 1, i did a quick search of ebay.com and half.ebay.com and found several instances of Civ 1 and Civ Chronicles for sale.
Admittedly, i'm not sure why at least one of the Civ 1 listings cost 70.00 (no box) where as Civ Chronicles, which includes Civ 1, multiple versions of both civ 2 and 3, as well as Civ 4, cost $35.00 (Brand New & Sealed in USA Retail BOX), but then i guess people will sell for what they think they can get for it...