Back in the day, when I restored cars for a living, I went out and bought a massive cherry picker. It's about twice as big as the fold up ones that are all the rage right now. Big enough to pick a 7.3 diesel out of a Ford F450 without pulling the core support. You get the idea.
I'd use it to lift the cars on to mine.
I don't know how the OP is going to do it, but that's how I used to.