In Kees's tuned 4LO 350 with 28 mm PWK's i am using the N68, JJH left a big stutter. I was planning on buying two sets of Polini needles one set contains a complete range of needles for one carb. I have seen these being used on the dyno bank when setting bikes up. No issues. I haven't bothered as the bike runs well and i haven't had the time to even think about fine adjustments.
JJH 130 mains 40 pilots Stock airbox ZERO missfires, stumble, hiccups or anything else. Zeel set to open PVs early and fully. Can't Imagine it running 'better'. And it burns a bit rich.. intentionally.