You sound like you're re-inventing the wheel...The ancients used simialar means of vertical transportation....
A modern day version can be found on the cart carrier picture at the bottom of the page on the link below....One thing you got to remember about a human powered design...Gravity is a MotherF#$##^

http://encyclopedia2.thefreedictionary.com/Elevator

If you truly want to impress him look into your design around lenear induction motors powered by fuel cells.

It Don't mean a thing if it aint got that swing.

Cool, Free, Johnny Smith courtesy of NPR..HERE
http://www.npr.org/ramfiles/asc/asc25.smith.asx