It must be remembered that the whole engine was designed around the concept of economy & reliability first, with dazzling performance not even on the radar, so cam timing is tailored to this end.
We can wake up the performance of these engines only so much with increased carburetion capacity [bigger carbs] but there is a limit to just how much air these engines will suck.

Using an excessively large carb [or carbs] simply means that the speed of the air flowing through the venturi[s] at WOT falls to a point where the carb can not always provide the right mixture, & this leads to all sorts of problems.
The dual throat, staged Webers that are commonly found on 2 litre engines [usually DGV's] seem to be a very good choice, but like all carbs, they need to be fine tuned to the application to which they are being used for best results.
Fitting a modest sports cam [which usually involves engine removal] will give the little 1200 engines in particular a refreshing boost in performance when used with one of these Weber carbs & make them a real surprise to most other road users.