Thanks so much for the responses! Ok- I know he did use the 14 in Unifit piece - because I have the 12 in piece in my possession - and saw the empty box that says "14 in" Unifit on it. That was my first burning suspicion - that he really used the wrong size. I myself purchased the toilet with the additional 14 in rough in part. So it looks like my guy did use the right part. It's true that maybe my rough in is 15 inches. I just needed to verify that you can't really botch this install. The toilet works great. It's just puzzling to me why we didn't gain any space. And if only the plumbing was adjusted when the floor was ripped up. But too late.
Maybe you are holding the 14" one in your hands, and the 12" one is under the toilet. Your guy could have been confused as to which was which (in the same way the contributor a few posts above was a little confused for a moment).
Clearly, something isn't right. If you had an original Drake (CST744S), and the back of the tank was 4" from the wall, that means you have a rough-in greater than 14". The Drake usually has roughly 1-1/8" behind the tank.
This would put your rough-in 2-7/8 inches greater than 12", or about 14-7/8 inches. The "II" series Totos, and the one you bought, should have .75" behind it. So you reduce the distance between tank and wall by about 3/8" by using the toilet you installed, if you used the 12" Unifit. Use the 14" Unifit, and the back of your toilet should be an additional 2" closer to the wall. So...you would reduce the distance between tank and wall by about 2-3/8" over your Drake. You would then have about 1-5/8" behind your toilet, not 4. (Or, to do the math another way, take the 3/4" that should exist between the back of your toilet and the wall, add the 7/8" that I think your rough-in exceeds 14", and you get -- voila! -- 1-5/8".)
You should have reduced the distance between tank and wall by 2-3/8". If you didn't, which should be obvious, and you didn't move the wall and you didn't move the flange, then something's up, and I think Terry hit it right on the head many posts ago.
Also, for what it's worth, a good plumber can "cheat" a toilet a little closer to the wall by the way he mounts it over the flange -- maybe as much as 5/8". If it's possible to do the same with a Unifit...hmmm. If you have a 3" flange, the hole in the center of the Unifit should be about 2-1/8", so if it's mounted (by fudging with the bolts) a little closer to the wall (say 5/8", there is plenty of difference between the two holes such that the hole from the unifit will still discharge satisfactorily into the 3" hole). Terry (and, I think, Jim) could tell you more about this, but it essentially means that if my math is correct, you could make this toilet look like it was mounted on a normal flange.
(Of course, it could be that you have a 4" flange and the plumber who installed the Drake moved it within the flange such that he reduced the distance between toilet and wall, and then this guy just installed it straight up, sucking back some of the distance previously-gained. Although that wouldn't account for all of it, it's a possible, albeit-remote, explanation.)
In short, using my Spidey Sense, I'm looking at the fact that you DID gain the more or less 1/2" difference between the Drake and Guinevere specs, but you DIDN'T gain the 2" you should have from using the 14" Unifit. Spidey says the guy used the wrong rough-in.
PS Did he read the directions?? Terry says that plumbers don't like to read directions, so he has previously commented (one of my favorites), that the list of required tools to install this toilet includes "Reading Glasses".