Looking at parts on Brickwerks' site I see that there's a stainless backing plate for the later brakes, which is evidently cut from flat sheet...

...but for the early brakes there's only this rather elaborate pressed steel item that has all sorts of creases and folds.

So being lazy here (to save taking the wheel off for a good look), can anyone tell me what it is about the early brakes that means a flat backing plate can't be used? Does it have to be shaped to fit round callipers and mounting bolts? I remember a thread on here a year or two ago where someone had made a CAD drawing of a backing plate - was that only for the later brakes (and are the Brickwerks stainless items made from that template)? I can handle Autocad, so would be up for drawing a flat steel version for the early brakes if that's feasible, so that they can easily be made from stainless as well.