16 British Standard Wire Gauge is 1/16". It is the only wire gauge that works for, but the higher the number, the thinner the sheet. So, they are about the same thickness as a mower blade. The width isn't actually important, but the wider it is, the longer it lasts.
They are probably less than a foot long - I haven't seen new ones, just used the ones that were on it when I bought it for $20 on ebay, and they were 6". The hole diameter isn't critically important, since it uses bushes - the bolts clamp the bushes to the rotating plate, and the blades swing on the bushes. Making a pair of bushes is not much of a challenge since I have an old toolroom lathe. If the holes were too small I'd probably drill them out - I've sometimes drilled holes in spring steel quite successfully using magic arts.
