Up to the early/mid '70s, few bikes had braze-on cage bosses and only on the DT. (There were exceptions with SR bosses, but not many.) From there to the early '80s, almost all (higher end) bikes had DT bosses and many had ST bosses.

Around mid-'70s was when top tube pump locations became popular and headtube braze-on pump pegs started appearing.. Before that it was seat tube if the bike had a DT cage boss and DT if it didn't. I raced a 1976 Fuji Pro with just DT bosses. Clamped on a ST cage and used a pump peg on the top tube.

Ben