Toilet drain size question.

Currently, my basement bathroom is stubbed with 3 inch ABS. The floor is concrete, and I will be setting the toilet on some vinyl tile over the concrete. I bought a flange that fits over the 3 inch pipe, but I'm not sure that there is going to be enough clearance from the pipe to the conrete hole to slide the thing on. I also saw a flange that fits inside the 3 inch, but of course this reduces the width. My question is, how much width does a drain realy need? I opened a wax ring package and to me it looked like the opening was about 2 and a half inches so I would assume that is all that is really needed. So, when I try to fit the outside of the pipe flange, and it doesn't work, could I use this inside the pipe flange. I wont have time to mess around wit this until the weekend, so I dont know if it's goign to work right now.

I'm also considering building a false floor and setting the toilet on that, and it would probably be easier for me to hide the copper that i'm installing.

3" flanges that fit inside the drain pipe should be avoided for the reason you have noted. If the flange won't fit the hole, enlarge the hole. Building a platform floor will forever have the appearance of a non professional installation.

HAHA!! It's going to fit. The builders left a bunch of paper and tape around the pipe between the concrete. So, looks like this thing is going to be pretty dang easy. I will just need to tear out some sheetrock, and install plumbing, and I'm done. HAHA!

Just be sure to bolt the flange on top of the finished floor level with only the thickness of the flange above it for the wax ring to seal properly. Tapcons work well with a concrete floor.
Good Luck!
Mike