

As Far as the bonding of the long side panel is concerned :
Besides the fact that the bus had fallen on it's right side, and also being around 56 years old , and having been subjected to stresses and twisting for all those years,unless you replace all the horizontal and vertical inner support panels with new ones you will not get it to bond 100% on all the surfaces. We did get technical support and advice from 3m regarding bonding these panels and were assured that the surface area of bonding that takes place over the surface area of the long side panel, together with spot welding the perimeter will be adequate bonding to support structural strength.
Even if you were to spot weld the panel on to the inner support structure you will find a lot of pulling and end up with the long side panel requiring a huge amount of body filler in order to get it straight, achieving the same end result as far as strength is concerned.
If Spot welding the panel in proved to be the better option, we surely would have gone that route rather.
The long side panel bonding practice is widely used in restoring splitwindow kombi's as can be seen on other international forums.
The method is also used in the manufacturing of new vehicles.
As far as the Exhaust issue is concerned , Tuffex do give a one year guarantee on their exhausts , so feel free to contact one of their suppliers nearest to you.