Gas and Oil Home Heating Furnaces - Need ideas for inside unit problem

I have a 3rd floor "attic room" that I am currently turning into a small office. The problem I have is that the inside air conditioning unit (sorry, but I don't know what this is called, it's not the outside compressor though) where the air ducts stem out from lays horizontal near the back of the room and takes up a lot of useful space up there. What are my possibilities here??? There is really no where else to put it, but I was thinking maybe purchasing a "vertical" unit that takes up less space and so I can build around it... will this work? Thanks so much for the input!!!

Changing over to a vertical air handling unit should be no problem providing you can re-connect the supply and return with transitions that won't cut down on airflow. You probably would need a unit with a side return.