Before joining the panel sections together I spent some time filing the joints until there were no gaps as much as possible. This allows much better and easier fusion welding. I used a faced piece of angle iron from my folder clamped to the bench to check the edge for straightness, as well as keeping it perfectly square. Came across a problem on both sides that the 58 ends were not as deeply pressed as the original 48 centre part of the wall. So what I did was tack together the wider raised sections first perfectly flush and then stretched down the narrow sections to fit.
Started welding up the centre part of the wall. Was tacked flat but the heat shrinkage pulled it down.
Planishing the weld area only brought it back flat. Came up really well and all lined up too.
The ribs needed some work to blend between the two different years. Using a similar shaped dolly, it was hammered with a soft mallet over a beater bag.
So the first big section of 48 and 58 panels are together. Trial fitted quite well to the donor floor as well.