Not many photo's of work on the hood. A slightly larger than required alloy sheet was cut and a shallow fold made on the center line. A board with a curved edge was clamped over the sheet, after carefully guesstimating where the side fold should start. Hope that makes sense. The sheet was then bent around the board forming one side of the hood. This was repeated for the other side resulting in a shape which was not far off the required result. What luck. A little tweaking with a rubber mallet and a length of round bar persuaded the front and rear of the curved folds to line up with the headlamp surround and dash.
A lot of time was then spent trimming the oversize edges to get the best fit I could manage, followed by clamping to the headlamp surround and drilling for the pivot bolts.