This afternoon (1st August) I clipped up a scan/print-out from my Parts Manual (15 on Plate CA) showing the radiator framework and studied the real thing, made measurements and marked out the net on some cold rolled 1.2mm sheet steel, cut out the basic shape with an angle grinder and fine cut some of it with my roller guillotine. I didn't use engineer's blue this time, but permanent marker, even though there will be a degree of error as the nib is quite large; but then again, much slack will be taken up by bending. I'll cut, bend and weld it up tomorrow.
Above you can see the radiator bay of the Goat Lady's van, which ironically, considering it had been abandoned in a field for 40 years or so, is in better condition than mine was when I got it; in fact my van had lost its radiator altogether. I am pointing to panel 20 [in drawing, top. Click on image to increase size] and most of the lower panel has gone, though you can see some of it to the right of the tap. I rescued the panel I am pointing to. I was excited because my van had lost this. It will be a pattern for a replacement to be made in the next few days.