Had to remove rusted-out cast iron closet flange in a basement concrete floor. Old flange was a 3x3, lead/oakum joint to 3" cast iron soil pipe.

Have not been able to locate a 3x3 flange of either compression connection style or lead.

3x2 cast iron compression flanges are available easily in this area, but soil pipe is 1 7/8 below surface of tile so a 3x2 doesn't quite reach top of soil pipe even if mounted flush with tile surface, much less have enough overlap to grab correctly.

I'm reluctant to use PVC flange due to weak support and not much to tie down to. There is only a narrow lip of concrete to support the rim due to profile of old flange. Tapcon screws through the flange would be open-air for an inch or so before reaching the concrete. Also, a PVC insert narrows the soil pipe opening that much further, which is another concern.

Possibly extend soil pipe upward an inch or so if there is a method to attach a PVC or iron fitting, then use the 3x2 cast iron compression flange? Other products that would have proper extension and stability for toilet?

what about using a 3" fernco doughnut to attach pvc to the 3" hub then filling the gaps in with hydraulic cement. After it dries, mount a brass flange to the concrete with better anchors than tapcons such as these [www.menards.com]
put a healthy bead of silicone under the brass flange before anchoring. You can cut the extending pipe off after that for the best seal. If you can't find hydraulic cement, give a call to someone that repairs concrete locally and they will probably be happy to give you advice.

There is NO hub. He has a straight piece of pipe going into his flange. He needs a plumber to lead/oakum a new flange OVER the pipe.

I could put oakum/lead into a new flange - if I could find one! So far no luck finding a 3x3 flange at all.

you could put a short piece of 4" pipe around the 3" pipe. make it just below the finish floor. lead and oakum the space between the 3" OD and the 4" ID. then use a 4 x 4 cast iron flange. pack and pour the flange around the 4" pipe you just installed. i would secure the new flange to the cement.

Thanks to all who replied. More ideas still welcome!

Interesting thought about using the 4" sleeve around my 3" soil pipe, and packing the gap with lead or equivalent.

I may have another solution. I have to repair a crack in the side of the old flange, and then I can reinstall it on the soil pipe using lead/oakum, Oatey Pipe Seal, or plumbers epoxy putty.
The top of the flange has enough structural integrity left that I would then install a Set-Rite extension flange over the top of it. The Set-Rite has a plastic downtube that goes inside the soil pipe far enough to handle flow correctly, and its flange will seal to the existing flange.

didn't you say you would not use a flange that went inside the pipe?

Not ideal, but it is at least a little thinner sidewall than PVC. And admittedly, outlet from stool is only 2 1/2 or so anyway.

I haven't measured a toto recently, but I thought the inside diameter of the trapway was 2.25 inches, and the outside diameter of the china was closer to 3.25 inches