Ummm.

Building a Rumford fireplace implies that you will be using it for heat and are concerned about the efficiency of the fireplace.

Pretty much any fireplace, Rumfords included, are pretty dismal in terms of efficiency compared to a wood stove or modern fireplace insert. A regular fireplace was technology developed in the 12th century. A Rumford fireplace is 18th century technology. That's still technology that's 250 years old.

If an attractive flame is what you are looking for, a wood fireplace is great. But as a heating appliances they are pretty pathetic.

Furthermore, fireplaces and wood stoves too are intensely labor intensive, fireplaces a lot more so because of their low efficiency. Most people use their fireplaces only bery infrequently.

Of course, you may be the exception, and already considered all these issues. Enjoy your fireplace.

Sorry the above response was the only one you got to your question. I'm thinking of rumfordizing my fireplace. The mortar between the firebricks is all burned out so something needs done before I can really use the place. I cannot afford a good EPA fireplace insert although that was my first choice. I dry stacked some firebricks into rumford design and the difference is quite profound in comparison to the original "firehole" design of the fireplace. I can't wait to get a round tuit. I'd like to know how your experience has been, or anyone else's, with rebuildlding your fireplace into a rumford design. I don't want to get too invasive and rebuild the throat. I think the original cast iron throat will be fine but it is about 6 inches lower than what is called for for a rumford design.

A proper throat is essential for rumford operation. A proper, tall masonry chimney is essential for any fireplace operation (min. 3-4' above the HIGHEST part of the home)

Here's a pic of my latest rumford build completed

Awesome, Berlin!
I'm trying to get a CSIA chimney sweep to come in and look at what I have before do anything. But Rumfordizing is what I want to do. My fireplace will be more for entertainment than as a serious heating appliance. So, efficiencies be durned...
You say a rumford throat is essential and I understand that. The only difference I see between my iron throat and a real rumford throat is that mine isn't curved on the front part. Mine is a flat piece of metal at a 45 degree angle. Sorry I don't have a camera to take pics. The back part of the throat is right at about 12.5 inches deep, in other words, spot on for rumfordizing. So, I will be able to have the depth of the fireplace right and be able to angle the side wall right. I just don't have the curved bit in the throat and the fireplace is about 6 inches too short but on my test run the flames didn't get that high anyway with the way I run a fire. I also wonder about the smoke chamber above the throat. Mine is angled back a bit so that the flue clears the roof eave. I hope I can find a sweep that is knowledgeable about Rumford fireplaces. If there's anything you think I need to consider, please let me know.

I doubt the csia sweep will have more interest in your project than he will in trying to sell chimney liners. A mason who knows about rumfords will be able to set up something nice (even if he doesn't know, pics and info about them will be all he needs); Most sweeps are not really good at that kind of thing.

The throat needs to be rounded, count rumford insisted upon it, and he's right. A mason could rip out the vestal damper and build a new throat with either cut brick or pre-cast ($$$) or, you could have a steel plate bent to the right curve and bolt it to the vestal damper, but it will not work well without that done. The smoke shelf is not very important, but the throat is.

I would look for competent masons, not sweeps for this project. Good Luck!