First, is there a fireplace in the center of the house that is pushing it down? If that is the case, the fireplace and chimney need to be removed; they are virtually impossible to raise.
The center of a two story is going to be very heavy; I would want at least 6 hydraulic jacks with 8ton capicity each spread around evenly under there. I would move very slowly, deliverately, and safely. If you decide to move a jack to another location, be sure to crib up what you have gained. Someone needs to be inside the house to watch for cracking or splitiing and to watch a level moved around often to check the progress.
I would only raise each jack 1/4" or so at a time, trying to get it all to going together at one time.
We would like to see pictures of the job, before, during and after.