Back again with questions. Working hard on a 1989 Thomas bus conversion. We have the metal walls and all insulation removed, and in a few places removed windows and put up fi erglass panels. We are planning on gluing rigid foam straight to the walls of the bus to insulate behind a wall facing. We've got a nice fiberglass epoxy for that step. Then we wanted to add vertical struts to the channel iron between the windows to attach the conduit and wall facing. Problem is, its not straight. As I can tell, the bus is straight up to the windoes, then it begins bowing in towards the ceiling. It seems to be a good inch more in at the top then midway down and to the floor. So how can I stud the walls straight from the top downs?