Which brings up an important point.. you'll need to move the eyepoint, at least a little, for the new interior model..
If I understand it correctly, the eyepoint position entered in the aircraft.cfg corresponds to the pilot's view point of the VC. IF your replace the interior model *and do not adjust the eyepoint position in the aircraft.cfg* then teh eyepoint is relative to the original VC, which will probably be misaligned with the new VC.
For example... if for some reason I reaplce teh 747's interior model with the Cessna 182 interior, and do not change the eyepoint values, my VC "view" will be from the original 747 pilot's position... somewhere "up there" .... I would have to then copy over the Cessna's eyepoint values. (presuming that both reference datum positions are 0,0,0 ..... which they aren't..)