i am going on a brown bear hunt next year and would like to do a standing full body mount. i know when they measure bears they talk about the distance from nose to tail. how big of a bear can i get into a room with 8 ft ceilings? are there issues with getting this type of mount thru a standard 3' door that everyone has in a house?

Those dimensions can be worked with, however a large brown bear won't be able to stand upright in a room w/ 8' ceilings, especially if you put it on a cabinet style base. There are lots of poses that would look better in a room like that and probably look better anyway.