I am not an expert in this field, but what would one gain from having billet wheel hub with bolt/rivet(CZ hubs) in brake liner that is an exact copy of the original (aluminium,magnesium, worn out)cast one. I can only think of the wheel hub being safer, maybe a touch stronger and heavier depends on what material is used. And i am prety sure that there was a lot of sand cast/billet hubs and parts on works bikes in 70'and 80'. And let just be honest. One dont have to have a CNC machine to make an old school wheel hub lads. Old school lathe, bench drill and bit of thinking would be enough to make most of hubs that dont use straight pull spokes.