8.5" Rough In

I live in a 1929 house. Our upper level bathroom has a commercial, high tank toilet with an 8.5" rough-in, and a 2" pipe connecting the bowl and the tank. The toilet does not work well anymore and we want to replace it. I would love some advice on the most economical, yet technically sound way of doing that. The options i am considering:
1. Use an offset flange. I have not heard the greatest things about them. Are there some that are better than others if i go with that option? Is 1.5" or 3.5" (to get a 10 or 12 incher on there) too far to use an offset?
2. Create a box in the dry wall to accommodate a 10" or 12" toilet and leave the roughin hole where it is. I have to bust some of the drywall to move the water supply down anyway because it's about 4 1/2' up the wall right now because of the high tank. The toilet that is on there now is also at a slight angle, so not sure how to box it so it doesn't look dumb.
3. Rip up the floor of the bathroom/ceiling below and move the rough in. Because of the age of the house, i am scared of what i might find and have to deal with, including the possibility of asbestos or some other major hassle.
4. Buy a 8.5" duravit toilet (for about a grand!! yikes) and install it. Would still have to move the water supply but with this option, I don't have to worry about trimming 2x4s in the wall, making a nice looking box, etc.
I'm open to any and all other suggestions.
Thanks!

I'm surprised that you found a toilet spec'ed for 8.5" rough in! The US standard for the last umpteen years has been 12", although toilets are also made in 10 and 14" (but often not as large a choice).

How easy it would be to move the flange would depend on what kind of pipe (probably cast iron) and which way the joists run and where it is relative to those joists. It might be fairly easy, but you'd need to either tear up some ceiling or flooring. To install an offset, you'd have to do almost as much work, so I'd opt to put in a standard rough at 12" unless the joists are too much of a problem.

Offset flanges come a a couple of variations. the one that looks fairly normal from above but has something like a 45-degree bend part way down usually works decent. The type that has what amounts to a small bowl with a (nearly) side outlet is very problematic. But, to replace the flange, as mentioned, you'd already have to tear up the existing stuff, so try to install a 'normal' flange at 12", then you have maximum choice on what to replace it with. Note, this is measured from the center of the drain to the finished wall (don't count baseboard unless it goes very high, like wainscoting).