After alot of fiddling i solved the gap OK with the ritchey comp headset..
First of all i ordered the Ritchey WCS headset bearing - which is a IS52-bearing that doesnt add as much height as the is52-one that followed with the headset/cover kit. They are physicalle both 8mm thick - but the 45degree angel-parts, are bigger on both sides, which makes the bearing give at least about 0.5mm (or so) less stack.
Then i removed the rubber sealing ring that is under around the edges of the cover - put a little bit of hot melt glue all around on the inside, put the sealing back fast and put it on and torqued down the headset. this made the rubber seal all the way down - and its not possible to see the glue from outside - the rubber closes the whole gap.
It would be better if ritchey just released different height of the rubber sealing, (like +0,5mm +1.0mm, +1.5mm and +2.0mm thickness) but this is alot better than before, and will certainly stop alot of dust/water getting there.