Thnx for all the great comments sofar.
Last night compared the values I got with an almost brand new Thor 200 and I got matching results, so I guess the aircraft side of the wiring is ok. The regulator itself is toast, on a side note: do not mount your regulator on the cage frame right below the reserve (I have a reserve behind my head). For now the regulator only became very hot, when the flight would have lasted longer it could very well have erupted in flames (which is not particularly nice, behind your head below your reserve....).
I attached a document stating the factory values of the magneto and coil.
Punt
Factory
Actual
New Thor
Coil
A -> B
3,5 - 7 KΩ
8,8 KΩ
9,5 KΩ
Magneto
C -> D
0,3 - 1 Ω
1 Ω
1 Ω
D -> E
200 - 500 Ω
282 Ω
250 Ω
Just to make sure I will be replacing the sparkplug, hopefully tonight I will manage to get some spare time to mount the motor back to the frame and do some testruns.
After talking it through with some local friends I think the max. power output of the accessory side of the magneto was too much ( max. 50 W) for the fitted regulator (max 6W) combined with the strobes which draw 4 W, causing the regulator to overheat and eventually drawing too much power from the magneto which resulted in substantial power loss due bad ignition (I flew at full throttle barely maintaining altitude), hence the wet and black sparkplug.
polini-coils-resistance.pdf