I remeasured and the center line is slightly less than 11 1/2 (more like 11 7/16) from the drywall. Im thinking about buying the Toto Ultramax that Terry recommends. Anybody have experience with the rough-in space on this particular model?

BTW, for those chipping away around a drain for the first time, a cheap air hammer takes care of the job in short order. Just be careful to aim the blows away from the PVC drain tube. My first experience was with a set of hand chisels, baby sledge, lots of brawn and many blisters. The air chisel turn this nasty several hour job into a 20 minute effort.

: This is unbelievable! I just did exactly what you have to do this evening. I had to cut the 3" ABS below the surface of the floor. What I did was to get it close, then I took a band clamp and put it on so that the bottom was exactly the right height. Then I took a PVC cable pipe cutter and sawed the ABS off. It's not the very best cutter for ABS, but it worked. I had to take an additional 1/2" off because I can never measure right. To do that, I used my 4-1/2" grinder. Again, not a professional way to do it, but it worked just fine. Had to rasp the slag off, but no big deal. Flange fits perfectly.