We believe early production bikes used this "clover" style flange. The circular-style flange drums are also common, but this style appears to be the preferred version.
All lug holes have clean, straight threads, and we have already tested lug fitment in each, and there was virtually no binding when turned in. So no burrs are present. Machined surfaces remain pretty clean and straight, and we are not finding any evidence of drum lining ridging or scoring, whatsoever, so the surface remains square. There is some light pitting, but it's very limited and mechanically insignificant. Lastly, you will also notice a smoothed spot on the drum outside edge. This appears to be native to the casting, itself. So in our opinion, this is not a blemish.