all of my lugs are cast and i can easily get 2-3 degrees on either side of their as-delivered state. simply expand the interior and make the parts an extreme slide fit. meaning, get them to fit loose on whatever tube they’re accepting. the casting doesn’t determine the design. the fixture does. when i assemble a complete main triangle for the heating cycle, though its in the fixture where i only add two small tacks total prior to removal, the interference fit is no longer an issue. i also think folks are too over-analytical when it comes to clearances. better to work on improving torch waving and pace than to beat a lug into submission.

everything above applies to pre-investment cast parts too.