Sloping Basement

I am considering the purchase of a house on the south shore of Long Island (New York State). I think homes in this area were built on swamp.
It's a split level house with 4 levels - ground level (garage, den, bedroom, bath) , 2 additional levels above ground level, and a basement one level down.
The 2 upper levels seem nice and straight with no noticable signs on settling. The 2 lower levels have both settled and/or sunk.
On ground level, the garage floor is cracked and buckled upwards in one section. The den and bedroom (behind the garage) both slope towards the side of the house. The basement is severely sloping to one side (I think it's sloping in the opposite direction of the ground level, towards the other side of the house). I'm not sure if the floor is cracked - I didn't notice anything but there's lots of stuff on the floor).
I asked the owner about it. He lives there since 1972 (the house was built in 1959). He finished the basement when he moved in and the settling has happened since. He said the foundation is fine because the upper 2 levels are straight. He thinks the concrete slabs sunk because the piles under them settled.
So here's my question: Is this something that can be repaired with some kind of reasonable assurance that it won't sink again? If I gut the basement and pour a new floor, how do I know it won't sink again if the owner is right about the piles and they're not fixed?
Or should I just forgot this house a and run the other way?
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<< Or should I just forgot this house a and run the other way? >>
If you have a high six figures income and need a hobby go ahead and buy the house. But practically, before signing anything retain a well qualified structural engineer familiar with the area to assess the problems and look for others. He/she can best answer your questions about repairs, costs, and the like. Honest information regarding pros and cons will help you make a sound judgement for purchase.Good luck.
Joe
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