Sounds like you will be able to keep it straight up, which is good. Also make sure the top of the chimney is 24" or more ABOVE the closest point 10' away... if that makes sense.
Other than that it sounds like you very well might be beyond building-code territory so just keep it away from combustibles...
The other option is out the wall through a thimble and then up.
You may need to also keep it up to 36" from the wall if it is near one (and not covered with some sort of masonry...)