Install Lion on a spare drive, then clone it right to your old ssd which will overwrite everything. of course, back up or time machine what you will need again. Then again, why not try the Snow Lep upgrade first and see how it is? There is a guide posted on how to make a bootable Lion disk in the Lion forum.
This sounds like old school Windoze thinking. Forget it. Just run the Lion Update and be happy. If you have unwanted apps or docs send them to the trash. This isn't Windows.
I did that on my MP last night. Works like a charm. Intel 80 GB SSD with SL already on it. Upgraded, ran the regular install. Got new drivers for my Kensington trackball.
I do not like Mail. Hard to see what I want to see. Found the trick to accessing the user library, but still a pain. I guess it will take a while to get used to it.
I also have a PPC app that is a must. Maybe someone will come out with a way to use that soon.