You have a finished opening which you want to convert to a framed doorway, as a form of egress to a porch you are presently using as a bedroom.
If your intent is to, in the future, advertise this as an additional bedroom, it is required to have two specific forms of egress.
A standard door is 80" tall. So the door will need to be shortened too compensate for the thickness of the jamb and any floor covering.
If the wall thickness is wider than a standard jamb width, you might consider installing a spacer panel on either side of the jamb.