The needles do work properly with the motor and cam, as it has idled with them before.
I re-build the SU's as it was leaking to much air passed the worn bushes and the AFR's would go dangerously lean on cruising. I re-build them from the parts of a second set of SU's that I had, selecting the best parts from the assortment a hand. Their is definetaly less play on the shafts after the rebuild, so I'm guessing they must be better. I've also sealed the shafts on the non linkage ends of the carb's with epoxy to limit any air leaks on to the linkage end of the shaft.