You mention the Ultramax II and the Drake II. You should also consider the workhorse plain ol' Drake.
As Terry points out, the Drake spec sheet says that the round Drake sits about 3/4" from the wall on a 12" rough-in. In reality, it appears to me that it's closer to what the spec sheet on the CST744E (elongated Eco Drake) says: 1-1/8". Have you measured your rough-in? Is it a precise 12" or is it off a little (or is it 10" or 14")? The original Drake can adapt well to a rough-in that's as much an an inch shorter than 12".
The round-front Drake CST743E is 26 3/8" back to front. Using my tape measure, it is VERY approximately 10 7/8" behind and 15 1/2" in front of the center of the closet flange. I'm eyeballing, so this is very rough, but it should give you an idea of the general proportions. If you need it more accurate than that, I am happy to get out the level and really do it right. Spec sheet: http://www.totousa.com/Portals/0/Pro...3E,%20V.05.pdf
The elongated Drake CST744E is 28" back to front. I have one of those as well and can try to measure the split for you if you want. [Edit: The distance behind seems to be about the same, so you can do the math on the front.] Spec sheet: http://www.totousa.com/Portals/0/Pro...EG,%20V.04.pdf
PS Like everyone else, we love our Drakes.