Having owned a Bob Jackson from 1974, built in late 1973... Hetchins was the maker with more credo at the time, a bit fancy... but a smaller producer than Jackson. In the period from 1972 to 1975 that I was directly aware of Bob Jackson's shop's output, fames could be ordered in any number of ways, extra braze-ons were an upcharge, but modest. Getting 20 to 30 imported at a crack was not a problem, build quality was variable, mitered tubes at the bottom brakcet? Almost ALL of them needed tapping and facing of the bottom bracket shell.
I got to meet Bob Jackson once on a visit to the states, nice fellow, as was his son, at that time I had one of his bikes, and we did discuss a new road frame. I asked him directly if he had any CAST bottom bracket shells, he said there were probably a few still lurking around, and to mention our conversation in the order, he would see to it that one was used. Never ordered the bike, got one of those new ones from a start up down in Carlsbad, California.

I will say that the paint work coming from his shop at that time was top notch and pretty durable, and the chrome was very good.