You have to be the most fortuitous guy in the world! I had to buy mine. :-)
Well, seeing that you "found" the house, you probably won't mind spending some big bucks to hire a building mover to raise the house up so you can put in a new slab.
That brings me back to the old law of physics, "For every action ther is a reaction". When you raise the slab, the house will raise 6" and walls and ceilings will crack. windows and doors may become out of square (if they where framed square in the first place).
Question* Have you already bought the home or are you using the word "found" as planning to buy?
If you have not bought the house, you are probably better off to keep looking.
What did your foundation guy tell you about fixing it?
I'm sure there are others out there that will have a different viewpoint but, I think you either have to do a major repair or stop using the front door!