Pond Girl,
If you decide to proceed with this project, I (and likely many others) would like to see your progress well documented. I think your plans are going to yield a beautiful feature and will be done on a fairly large scale. This being the case, it would make a great study on waterfall features in ponds.
If/when you kick it into gear, please start a separate thread, take many pics, and keep us up to speed with all the progress. Maybe pop it into one of the pond construction forum categories...?
thx