Modern Vespa

Long story short, new engine build. Smallframe with a Pinasco Zuera top end. Also new crank, flytech ignition, plccorse clutch, Dellorto 24mm carb. The motor is port matched, air intake enlarged.
I had an air leak which I fixed. The Scooter idles fine, the flywheel is noisy, but I guess that's normal.
I had to up the idle jet from 50 to 57, due to not returning quickly to idle. The main jet is currently 127. Needle is D22, atomizer AQ264
I'm having trouble with mid range acceleration, and wide open throttle.
Motor will scream to about 9000 rpms then nearly cut out and back to 900 rpms herky-jerky like. It almost seems fuel starved.
I pulled the carb and swapped out the needle and atomizer. D29 and AQ268, but everything got worse.
I put D22 and AQ264 back in and moved the clip to the lowest position on the needle, but the problem remains.
I'm confused about the needles. Does a larger number mean a fatter needle? Hence a leaner mixture? If so should I leave the D22 needle in place and use the AQ268 atomizer?
Or maybe I need a fast-flow fuel tap.
It would be nice if I knew what the hell I was doing. Not sure I like the Dellorto 24mm

Try to follow John's thread was 130 DR loss of power - now CP21 jetting

Different carb and different issues but the the same concept.

btw: The D22 and AQ268 is the richest combination

Edit: Does your carb have a Pilot jet atomiser fitted deep in the same hole?