Tonyfoale,
That is an old carb you have showing. They're rare.
The carbs I had been talking about were the Amal Concentric Mk1. They replaced the Monoblocs in the 60's through to mid 70's before the advent of the Concentric Mk2. The original Mk1 had a removal pilot jet but most came sealed. Only the new Premiers replacements now have removable pilot jets once again. All the Concentrics came with uncoated slides and were made from the same pot metal as the carb body - hence the galling action between the two similar metals. Again later could you buy replacement slides that were chromed and later still anodized slides. All are only available in the stock size