I finally dug out the Thruxton needles, the Trump Part number on the bag says T1245031 and they are stamped NBZT with the B being a weird little B with a line in the front of it. The B is half the size of the other letters as well.
If you order them, go by the trump part number anyway, most shops will give you a blank stare if you ask for a NBZT needle jet. And don't forget to get 2 of them, one for each carb eeh?

A word to the wise is not necessary. It is the stupid ones who need the advice. Pat