Ballast can be external, internal or a combination of both. A boat with all the available ballast outside the hull is more stable to the wind, but a low center of mass can cause a lot of rocking, and this kind of ballast is permanently attached to the hull. If you need to lighten the boat in case of an emergency or if you need to take more weight with you - there`s nothing you can do about it. You can also consult with these guys concretecontractorsfortworthtexas.com. I know they`re good professionals when it comes to concrete, and I haven't contacted any other companies yet. Btw, you can make a new keel for your boat yourself, I saw some detailed instructions.

I had to do repairs and I understand that every delay is just a loss! It's bad that they suspended the work.

Looking at a home built mono with a concrete fin keel filled with lead & cast steel pieces.
The concrete is painted with copper coat bottom paint same as the rest of the hull below the wate line.
The concrete finish is ruff.
My question is shouldn't the concrete have been smoothed and faired with epoxy filler and then painter with epoxy primer and then painter?
The boat is in freshwater Canada where the winter temps can get into the -30's. Boat get hauled out for winter.
My concern is the possibility of the keel to absorb water, freeze & crack.