I think we're outa luck, Sol. The two wources I cehecked are about as authoritative and we're likely to get - and they have no differences in the lyrics. There's a site you can explore, http://www.johnnymercer.com/index.html - maybe they'll come up with something different. I have only one CD with Mercer himself singing - 20 cuts, and it doesn't include "Moon River." I've looked long and hard, Sol - and all I've found are the conventional lyrics. I tend to think there is no alternate "original" version
Take a look at this page, a list of recordings of Mercer songs. Do a find [CTRL-F] for moon river. It's amazing how many recording there are of that song.
-Joe Offer-