I started on the back wall part. I had to drill some pointwelds out to get to the rust behind the sheetmetal and then weld it up again. I sealed the seams so the water can't get in again. when I placed the wall on the car I learned that you have to wait with bolting it down to the floor untill you have the roof in place, otherwise the roof will not fit to the front window (about 1 1/2 inch sort). it took me only some 20 bolts to lossen and afther to fasten again.
but first, I sand blasted the roof in my home made blasting cabin. there where two bad spots on the back wall and some holls to repair.
see the pictures in my next reply.
cheers jaap