I recognize the problem Giorgio, if wifes not there to “interrupt” (caring) all days meals tend to be at the evening when working. 
Testing with a drill and search the best point is a good way, i do it exactly the same way, use to mark the “range” with a pen.
Some magnetos are possible to change rotation, often there are markings, arrows, or right/left stamped on parts that could be moved. Sometimes the piece for opening the points are a loose part, just pull it from the axle, and push it on the other end first.
But this are mostly “universal” aftermarket magnetos.
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When a magnet or coil rotates in a magnetic field, a voltage is induced in the coil due to the changing strength of the magnetic field. When we look at how quickly the strength of the magnetic field increases in the core of the coil and thus the induced voltage, we can see that this is not a sinusoidal curve, because at the beginning, when the core rotates in the vicinity of the magnet, the strength of the magnet increases rapidly and reaches its maximum, then this strength does not change and the induced voltage drops,… the sketch shows the area where the spark is strongest…
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as the breaker plate has yet the long slots for flexible ignition advance regulation, we revitalized them …it has about 23 degrees…we achieved in every extremity (and beetween) a excellent spark. this maybee useful because changing 1 tooth of the gear, how reported, canges for 13,3 degrees…
who can explain the numbers of the capacitor?, generally they not show the microfarads…or only in a code…
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the next argument is to think about the regulation…
as we need a throttle in the air intake, the regulation should act there…(in diesel version acts on the diesel pump by fork 1)
the throttle command cable goes to 5 and acts on two flat springs 4…
the centrifugal regulator has 6 balls (3) and acts on fork 2 for moving fork 1…
fork 1 than will have some connection pieces to the throttle…
speaks something agains this ?
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Giorgio,
Based on only a few minutes of research, this is my guess.
0.65 microfarads at 6000 Volts. It appears the average capacitance for a normal points ignition is 0.20 to 0.30 microfarads, so this would be larger than average. It is a magneto type ignition, so that may be the difference. If the sparkplug sparks, and the points don’t degrade / pit, its all good!
(your guess may differ!) 
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Hi Giorgio, i guess your governor would work with some “trial and error” hard to see with only pictures, but easier to test.
Make all connections and springs easily adjustable.
And a smooth moving throttle.
As for the capacitor i think Mike is right about it, 6000 volts seems much though, i have used 600 volts capacitors, and they hold up well, the modern square types, like a tiny box, works well, Evox Rifa for example.
I can’t really tell if the capacitance are higher on a magneto, best would be to test with a capacitance meter, this often works good even on “burned” capacitors.
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Giorgio, I will list just a few features of throttle valve regulation:
-Goran wrote nicely that the valve must move very easily as well as the entire linkage
-a diesel engine with a high compression ratio creates a very deep vacuum, which means a relatively high force on the throttle valve at low load, which means a large friction effect in the valve shaft. If the shaft has a larger diameter, the friction is greater, while a small diameter shaft represents less friction, but faster wear, make a compromise.
- the centrifugal regulator should close the throttle valve with its effect, and the spring should work in the opposite direction, with which we set the desired speed
- The cross-section of the throttle valve should not be too large, because this will cause large forces on the valve and thus difficult movement at low load, it is better to choose a smaller cross-section of the valve
Let me give an example:
-an engine with a working volume of 1 liter (1000 cc) and CR 1:15.3 has a combustion chamber size of 70 cc
-an engine 1 liter with CR 1:4.3 (Acme CR example) has a combustion chamber size of 300 cc
These data show that the first creates a much larger vacuum and practically completely empties the cylinder with exhaust gases and can thus capture the full volume of fresh fuel-air mixture, while in the second case almost 30% of exhaust gases stagnate in the cylinder, which greatly reduces engine power
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tone, this is actually my thought, if the regulator is able to move a throttle…because in the diesel version it must only move a little part of the pump…
so the vertikal lever, what replaces the pump, i think must have ball bearings for easy move…
also eventually the throttle ( this a thought now, when i read your comment) ?
what diameter of the throttle you would try for our motor?
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A tip is to search the net for small ball-bearings, they are often to be found for radio-controlled toys, very cheap, some are around 1€ each.
I have found as small as for 4mm shaft for mixers, and with rubber seals. 5-6mm are pretty common and should be good for a throttle shaft.
Just get some thin pipe that fits the outside of the bearing, and spot weld or solder to mixer pipe. (With shaft in place, to get all lined up)
Also the throttle “flap” should be centered good on the shaft, it makes it move easier, minimizes drag that tends to close or open it.
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Giorgio, your engine has 707 cc, which I could compare with my “new” engine, which has a working volume of 920 cc, but on top of that, the throttle has a diameter of about 25 mm, I think this diameter will also perfectly suit your engine.
A few more words about magnetic ignition … when the magnetic field strength starts to increase in the coil core and the switch contacts are closed, a very large current starts to flow through the coil, since the primary winding has a relatively low resistance due to the “large” wire cross-section. When the switch breaks the circuit, a large voltage increase occurs due to the “inertial” effect of the coil and also due to the further increase in the magnetic field strength. The capacitor must absorb a very large current at a low voltage at the moment the switch contacts open, so a larger capacitance is required, if we compare the ignition with a 12V battery, here the resistance of the primary winding is higher and the current is lower…
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i have here a handfull of little ball bearings, my son collected them always from electric and other stuff from the scrap…
about the throttle…if i make the butterfly throttle elliptic shaped, and in close position,let us say ,set at 60 degrees instead as the common nearly 90 degrees, would this reduce the vacuum (and with that the friction on the bearings) and leads to a easier moving?
also, at the under position, where the throttle shaft comes out of the pipe, i thought to make a regulable point bearing sustainment, what keeps slightly up the shaft, in way the round (or elliptic ) throttle not makes friction on the throttle pipe in the under part…maybee this can sustain also ball bearings here…
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