I think Mike offers a valid diagnostic here but I've not used that method before. Have you used this method before, Ed?
A method common in the SU carb world, absolutely NOT precise enough for Webers.
I agree with Ed, RJ but as well with Gordon.
Main issue in my opinion is the fact the TO needs help to make a proper diagnosis. Means not help from ARBB, but from someone who can check the car.
Maybe it's just a synchro issue, maybe the 'rebuild' went wrong.
There is a point where an individual should realize the need of external support to the car. Not virtual from the web.
Just my 2c of resolving unforced errors created by PO's or forum junkies.
Btw: My experience is that on 85% of all carburetted 105/115's ignition timing setup is wrongly adjusted. And RJ is fully right to concentrate on the M mark.
I've experienced in many cases that folks turned the dizzy by error when fiddling back the carbs to the m/fold. From a pro mechanic point of view it's stupid not to check ignition timing 'just because engine ran well before dismantling'.
Don't limit your diagnosis horizont but exclude unlogical check points first.