I know that quite a few folks use a fork lift truck mast as the elevating mechanism.
Becomes a simple enough task of attaching to the floor and suitable brackets on the upper level.
Fork lift is usually a one way cylinder and AC powered hydraulic pumps are relativly cheap. Hydraulic power for up and gravity for down!
Hydraulic check valve would provide necessary safety measures.
A 'man cage' would be made to sit on the forks.
Many if, not most fork lifts, get scrapped with the mast and lift cylinder still usable, generally engine, age and accumulated other issues render them uneconimical to repair/rebuild.