Concrete Filler Material in Vintage Floor Safe

I have an old floor safe that will no longer be used as a safe but more as a piece of furniture inside the house. Currently it is under a blanket in the garage and essentially useless just sitting there. My plan is to de-weight it by removing the concrete filler material inside the door and behind the inner wood panels (the interior pieces are still there but had been removed by a previous owner).

I've had the material tested for asbestos and it is safe.

My question is, are the components for the dial and bolt assembly attached/welded to the inside of the metal door, or are they held in place by being embedded inside the concrete? I don't want to remove the material if all of a sudden the entire lock mechanism is just floating inside the shell of the door.

To take the place of the removed material in order to reassemble the safe, I was planning on using either epoxy resin or rigid foam insulation.

Any time we want to move the safe we need a crane and to be honest its becoming a pain in the ass and also a source of damage to it. It's simpler to lighten its weight and be able to move it more conventionally and with more care.

To have even a chance of answering your question, some pictures might help.