Thank you all for the answers.
I think I“ll start the (easylooking) job the next days. So when I understand all points:
1) lift her as usual
2) rest her under the crossmember with axlestands with one far away from the other as possible
3) give the kingpin a support at the lowerend/ down fixingplate. The spring must free of tension or only light tension.
4) undo the topscrew with the nipple and fit the BRB. Fix it in a way that I can move it in position.
5) now the surprise… I noticed some holes and hope they are matching the lower fixingpoint. But now, welcome in real world:
drill it.
6) fixing the top screw - is there a specific torque numbered?
7) fix the lower screws.
8) fit the wheels and ground her back. Ready…
René