If it were my problem, I'd pay a structural engineer to look at the
holes and surrounding conditions above and below. Interview engineers
until you find one with experience in existing masonry structures. Some
engineers are excellent at new work and not comfortable with old work.
(E.G., 100 year old brick building in an area of questionable soils
with large stepped crack in one outer wall. One engineer recommended
tearing it down while a second recommended monitoring the crack width
for movement. Thirty years later, the building is still standing.)