I have this spare bonnet, as well as the grille, from a 1952 Willys Wagon that came with the 58 Truck when I bought it. I think it was deemed too hard to repair as it has bowed down across the middle of the bonnet a good 16 mm- 5/8", from someone walking on it. Most of the damage it right through the two vertical sides of pressings.
Something had also pushed up in under the front support as well causing a bulge on one side near the same pressing line.
So took out the support to get full access to the damage and will remove the rear one as well.
Really hard to show but you might be able to see the big gap under the ruler edge that you can easily fit you fingers underneath in the middle of the bow.
I worked up the creases and dents along the pressing and is looking a lot better, but still not good enough. You might spot also the middle of the bonnet also still sags down.
Time to get creative. If walking around on put the bow in, it should get it out! Supported the front with my small beater bag and gently pressed down on the worse spot. Wore sneakers rather than my steel capped boots to get more feel and less hard edges. Would do a bit and then check with the straight edge noting where more was still needed.
Just about there now and a few shrinks with the shrinking disc should get the last millimeter.
For the middle I placed a block against the side of the house and tilted the bonnet until it was only just being held against the block. While holding the top and ran my foot right down the middle with even pressure and it came out rather well. I put these techniques under 'primitive but effective'!
On to the 58 bonnet now. I stripped out the supports ready to take the dents out of this one. Noticed this later one the that it had more spot welds on inner edges of both supports which seems strange as that is usually not done.
These has dents all over it and these ones near the front as well. Two to the left of the trestle and one to the right of the pressing line.
Once I have the dents out I will decide which pieces to use from each bonnet. This needs to be made 220 mm-9" wider over all. It is not just a matter of adding a section from the other one up the middle as the centre higher part sits over the grille and this is only going to be 120 mm-5" wider by adding 2 extra grille slots. The other 100 mm-4" are over the headlight area, 50 mm-2" each side, which is the lower part of the sides.
To make the other bonnet wider on both sides of the pressings, I would cut the pressing area out of one and then add sections back in, like what has been cleaned of paint on this one, with the extra required width. Still means four long welds that I have to get perfectly flat and distortion free, but any other way would mean 6 or 8 welds! Another section also has to be added across part of the back of the bonnet when the centre part comes forward. I found that hard to explain so hope it makes sense?