I had spoken to very well known wheelbuilder who writes commercially on this subject and after explaining my situation he gave me a advice on the 120kg (= 22 nm). However i'll have another go an go lower to around 100 kg (19/21nm) and see if that helps.

I also checked with similar wheels with the same rim and # of spokes and it also came around the 120 kg or between 20 to 23 nm.

I have however a 1.8 mm radial wobble wich in my eyes is too much so i have another go tomorrow and see what happens.

It's a difficult situation realizing theres no specs from the makers on this subject for all good reasons as explained.

Nevertheless i appreciate everybody's contribution on this subject.