"That doesn’t translate directly to a 44% richer mixture, because the pilot jet, the slide cutaway and the air bleed drillings in the needle jet also affect mixture at these small throttle openings."
TT, you left out needle clip position.
Only trying it both ways ... i.e. new #106 vs the OP's existing #107 with a lower needle position will definitively settle it.
I always like to go with factory settings, so I would go with #106 in clip setting 3.
BTW ... from the Amal co. " Something that crops up all the time is whether you count the needle clip slot from the top down or bottom up. With all Amal carburettors the clip position is top down."