Estate meerschaum-- Total Loss?

It's not a total loss. It reads like you have an old pierced style draft configuration. That is, the hole is drilled down through the shank, and then the chamber is pierced to meet it. This results in a kind of j shaped draft. It's hard to clean so most old timers didn't bother. They'd smoke it til it clogged and get another pipe.

Sending it to a repair guy would be easiest. I'd expect any one of them could clean it up and fix it. But it might cost you as I think it would take some time. Plus old meerschaums can be delicate and some people don't like working on them.

If I were doing it, And I have done more than a few like this, I'd start by straightening a paper clip, bending the end a little, and using that to open the draft from shank to bowl. By sawing it around in there you can eventually loosen enough crud to allow a regular bent pipe cleaner through. Then eventually a lot of scrubby cleaners to get it clean. Dip them in alcohol to dissolve and pick up the crud.

I haven't ever fixed a chamber break through. I avoid pipes like that. But I guess I would use a dab of epoxy of some sort to seal it. Then I'd cover that in the chamber with pipe mud up to the draft hole.

I think all that should work and get it smoking fine. Take your time. Don't get frustrated.

Use some sand paper wrapped around a dowel or something to smooth the chamber walls and get them straight and even to the rim.

there's a dug-out portion of the cake which pokes straight through the bottom of the bowl.

Click to expand...

I don't understand what you're trying to describe.

If the pipe's bowl has a hole in the bottom, I'd forget about trying to restore it.

I will revise my earlier position. I thought you had a hole through the bottom of the pipe.
Some really old meerschaums have the bottom of the chamber carved pretty roughly. Sometimes the bottom isn't rounded, but tapers in a triangular manner to the draft hole.

Or you might be seeing the piercing I was referring to earlier. Instead of a round hole, it looks more like a cut line piercing into the draft passage drilled in the shank. If I'm reading you right, that's probably the way it was made. Without a pic it's hard to say what you are seeing.

Just carefully scrape out the cake and see what's left. It won't affect smoking either way.
Here's a pic of a pierced draft hole in an antique claw meerschaum. Not great photography, but maybe you can see what I mean.

Oh, cool! The hole had a piece of tape over it.
Okay, I stand by my original advice. Clean the crud off the outside. Use soap and water. You can clean the bowl surface that way too. If it won't come off, you can wet sand it lightly with 600 grit. It may affect the etching design a bit. But so what. Put a dab of epoxy in the hole. Mix up some pipe mud and dab some into the depression inside the bowl. Good to go.
Looks to me like someone drilled out the air passage and went too far.
You can also wet sand the rim to get the black off. Wipe it frequently with a rag too check your work. Use Micro Mesh polishing cloth or pads to hand polish the bowl. It will look good.