Christopher, you can still find the 3.5 gallon flush toilets. Sometimes you can find a plumber that will part with one, have even seen a few at garage sales.

And not all of the 1.6 gallon flush toilets are the same. Here is a comparison of 1.6's,

http://www.terrylove.com/crtoilet.htm

Here is another article that you might find of interest,

http://www.jimpoz.com/jokes/toiletPolice.html