No reason at all why that ''diet version' approach wouldn't work-I'd try and use some aerospace grade alloy sheet for if I were you though-.....I've just measured up a backplate screw-I make it about 2.2-2.3mm....very odd! M2.5 is too big, M2 too small-you might have to be a bit careful with your material thickness so you can use the original backplate screws....as these seem to be an obscure thread...and being Japanese-almost certainly a metric one-but probably JIS rather than the international ISO range of metric....I'm guessing they're probably M2.3-which is a genuine metric thread-but a very uncommon one! To make matters worse there is a fine thread and a coarse thread variant: M2.3x 0.4 and M2.3x 0.45...so the chances of being able to source slightly longer machine screws (the originals are 5mm thread length) in those thread variants are virtually zero....leaving you the option of either keeping the originals or tapping out the crankcase holes to take a US size-2.56 for example is fairly close in size [and the thread pitch is .456mm....so if the originals are M2.3x0.45, your 2-56 is almost going to fit if you need a longer screw to secure the radial mount....I guess it becomes your call depending on how thick you make the radial mount....and whether you counterbore for the screw heads, like in the original...

ChrisM
'ffkiwi'