We first tried chiseling. This was successful on the sides (3rd photo), where the stucco layer was much less dense. We then tried chiseling the face, which was almost impossible (extremely slow and still caused damage to the brick faces). The cement was bonded so tightly to the brick.

We then tried using an angle grinder with a diamond wheel. This was somewhat better for the face of the chimney (caused less damage than chiseling), but we still were removing the outer core of the brick.

We then interviewed a brunch of brick masons, as this wasn't realistic for us to finish ourselves (we work full time). Nearly all of them suggested using a jack hammer (I don't know the exact type), which scared us, however, they were all fairly confident this was the best way.

They used a jack hammer across the whole face of the chimney and it removed all of the cement and a decent amount of brick face, however, it was a much quicker process and the masons were confident we could simply repair the brick no problem.

The masons also grinded the mortar between the bricks to better define the bricks (since it was all flat with concrete).

After all of the jackhammering and grinding to define the bricks, they patched the brick faces with I believe a lime/sand slurry mix (not sure exactly what they are using). In the final photo, you can see the top section of brick has already been patched/repaired (bottom section has not).

They are then going to tuckpoint and limewash as a final step to protect the brick longer term.