Hi Sean, Julian is on the money. I imported my bike from England in 1983, where it had been rusting away for years ( likely not many years use after 1961 before it stopped ) and probably had been immersed under water - the gearbox internals had to be thrown.
The rocker feed is split and has a rubber connector sleeve. The surface of this rubber sleeve is "dimpled" for want of a better description. My best guess is that this rubber is original 61 years old or may have been replaced in the first 15 years - it fits OK, has no clamps and doesn't leak. I think it a great improvement - to remove the rocker box, just undo the two banjos at the rockers and pull the copper line out of the rubber sleeve. Saves disturbing/undoing the oil tank fittings. I did watch it after I fitted the SRM oil pump with larger scavenge flowrate & pressure and no issues so far.
I measured the banjo orifices - orifi? in mine, and they are 1.2 mm = 0.045". The standard oft-quoted size for my Flash is 3/64" or 1.19mm. So backpressure is also normal for my setup and hasn't blown the rubber off yet.
I think Gold Stars were 3/32" or 2.35mm, much larger than the Flash.
Col