The basement slab in our 150 year old house has seen better days. It
has settled with the center about 7 inches lower than the
corners. Also there are cracks and many "rough" spots.

I would like to refinish the surface for a basement workshop and am
considering several options:
1. Add a new cement topcoat to the surface to cover cracks and rough
spots and partially level the floor (I don't expect to be able to
make up the full 7in height difference but that will only primarily
effect the edges and corners)

2. Dig up the old slab and replace it

3. Do nothing?

- Any thoughts on what the best way to go is and what might be the cost?
[Area is about 700sq feet and we are in the Northeast]

- What type of trade person do you call to do this type of work?

Thanks,
Jeff