Today I received my Walther part no. 2743776 by mail from Krale Schietsport in Staphorst.
I first compared and measured it against one of the front posts I already have.
It is indeed 1 mm higher.
I then measured the hight of the old front post with shim . That's 5.8 mm. Without the shim it was 5.0 mm, I had to add 16 rear sight clicks to get on target with the 5.8 sight post (compared to the 5.0 mm without shim) I added another 4 clicks.
After the above change I had some range time with it and I'm really pleased with the sharp sight picture I get now.