thanks for that chart! it tells me that I'm probably going to have to cut off the CI hub maybe an inch below floor level which might not be too easy even with my recip. saw. maybe a "snap cutter" could do it?
Have you figured out what carrier you are going to use. Center of 3" santee branch to bottom of fitting is only 5"
Depending on the how high you want to sit the W.C. your CL of santee branch can be as high as 9 1/2 " but you only need 7" [ 5" + 2" (existing pipe sticking out of floor )]
here are some specs on a Zurn carrier for example only. Don't know what you are planning to use http://content.zurn.com/web_documents/pdfs/installation/C24.pdf
The ABS spigot O.D. is a little different than the cast iron. use a mission or Proflex banded coupling Not a no-hub coupling.I'm going with a regular "rear discharge" toilet made by "Niagara". this will mean chipping the concrete around the CI pipe going into the floor so I can cut that pipe and get a sanitary tee in there and maintain a 4" rough-in. looks like "Charlotte" has an ABS street tee which will do it. it has a spigot on the bottom and hubs at the top and inlet.