I used to prepare bikes for the ISDT and others.
those holes were used to lock wire parts together so they could not be changed, ISDT, Welsh 3 days, Scottish Six days all that sort of thing you had various key parts wired together by the scrutineer.
they were also paint marked, sometimes one colour often a patch of two, not big, patches less than a 50 piece.
I would strongly urge you to take great care, search the bike for paint tags, on wheel hubs forks all over, you may well have a very rare and historic bike.