I have a single carb 34 PICS 6 on my 83 since a few years. It runs very well onl there is a little "gap" between idle and full throttle. By coincidence i found a history about someone mixing a 2cv4 engine with 2cv 6 cylinders and heads. He had put a bigger pick-up jet in. As i couldn't find one i did buy a set of jet drills and got to make one my self. I did a very short testdrive there was still a slight gap but the car accellerates like hell....
See how it turns out. Maybe i have to adjust the injection pump a little.

The "gap" between idle and full throttle coinsides with the working travel of the pedal.

Yes but this carb has 2 jets one is to bridge that gap. But the petrol has changed with the E10 mix so it needs a bit more. I had a longer drive today, after warming it ran very well. Uphill it keeps pulling.

Are you saying you have a flat spot, like, a hesitation?

Yes like that, i still have to adjust the accellration pump. I read somewere they put a drill bit between the throttle flap to find the exact point were the pump should start injecting fuel.

If you look down the carb bore, and pump the throttle, does it squirt fuel? does the pump actually work is the first test.

I adjusted the pump lever a bit. It is now almost ok but i think the 0.65 jet is a but to much i will test a 0.55 one.