Old wood floors unlevel, use as subfloor for new flooring or not?

Hi,
I have an old house I am remodeling, built 1917 or before. I have pulled up carpet over the whole house, which revealed pine t&g flooring. I have had my house "leveled", supports put in the crawl space every 4-5ft and the joists have been reinforced, etc. The floor is still unlevel in a few areas, mainly towards the center of the house and a slant to the North side of the house. The t&g floors are nailed directly to the joists there is no subfloor.

What is my best course of action?

1. Ripping up the flooring to expose the joists and crawl space under the house and install a real subfloor? Really seems like a lot of work and would still have to address how to level the floor.

2. Somehow use the existing old wood floor and level the surface either using wood or a leveling concrete?

3. Install either laminate or tile on the leveled floor.

Right now I am "leaning" towards using a self leveling concrete to pour directly over the old unlevel wood floor and then lay down laminate or tile. IF this is something that is good to do, do I still need to put cement board down for the tile, or any other type of board for the laminate or tile??

Why would using the "self leveling concrete" not be a good way to level the floor? Pros/cons? What prep work would I need to do to the floor to use this stuff if its possible.

If the "self leveling concrete" is not a good idea, then how about trying to level the surface using wood, and how would I go about doing this? Seems like it would be very difficult to cut the wood right to level a floor over the whole surface, or at least good enough to put down concrete board for tiling.

Any help is appreciated.

 

only downside to levelling compounds is that they shrink/crack over time and this can affect whats on top. i recently worked on a floor where shingles were used to take the highs/lows out of a subfloor...layered as required, seemed to work as the house is 40 years old as was the flooring in it.