Sorry about showing up as three posts in a row, but I decided to make this subject its own topic and did it in an awkward way (rather than bothering Erling with it).
Responding to Mike, in looking through Bacon's "BSA Twin Resoration" book, I was surprised to learn that in early engines, up through XA7-450 in 1947, neither rocker spindle was directly oiled. Then, after said number, the exhaust spindle, only, was oiled, until 1949 when oiling of the inlet spindle was added. All this is very interesting, but I am still confused by the two different sized holes I have (in the banjo bolts, that is) and hope someone has an answer.
Richard