From memory the factory BRB's don't have the welded hole reinforcements either. Not sure if your tyre rubbing blocks were a factory fit but probably a coincidence the mounting holes worked for your BRB's. Regarding elongated hole for kingpin bolt fixing, it's not ideal but the washer underneath bolt will spread the load and hold them in position as it forms it's own index on BRB when tightened. You can always check these witness marks at kingpin/bush change to see if its remained in position.
Finally remember BRB's remained a factory option to the end of Classic production.
