The correct way to straighten out the bow is to sister new floor joists on the sides of the existing joists. The problem is, this creates a whole new set of problems, as in, squeaks, loose flooring, Problems at the joints in the existing floor...
What you might try, is to just jack the floor back up and see if it will straighten out as is. You might get a pleasant surprise.
Typically, We dig shallow, level bottom pier footings, Lay a 16" stepping stone in the hole, stack blocks on them to within 6" of the joists, lay a 4x6 across the top of the blocks. Then we put the jacks close to these piers and raise the floor by jacking the 4x6 against the floor, shimming the top of the piers as we go with 2" 4" 6" blocks and steel shims until we get level.
In your case though, A concrete block flue needs more. A deeper pier footing 32 to 36 inches deep, 30 to 36" square at the bottom, pour 12 to 16" of concrete and at least two 8" concrete blocks wide, 24" x 24" would be better. Mortared and built perfectly level and plumb. At the top, you need a barrier between the concrete and the wood. A piece of steel or aluminum would work there. Also you need to add wood on top of the pier so the joists are not bearing all of this load. You could add blocking between the joists. cut them to fit snug but not too tightly. You want to be able to position them easily. No banging and beating on the joists while they're under this load. Use screws to fasten the blocks. Make sure the blocks match the width of the joists so they will share the load. One at the back, one in center and one in front, in each joist space over your new pier. Sounds like overkill but structural failure would be overkill on your pocket!
As I sit here re-reading... The best thing you could possibly do right now would be to get a contractor or an engineer in there to assess the situation. A certified wood burner installer may be able to run steel triple wall pipe and you could do away with the blocks all together. There are options you need to consider and there are things there that I can't see that would change everything.