Hallo Uwe,
Greetings from Germany too !
One other detail to check is to make sure the distributor drive gear is not bottoming out on the block.
Clevelands "like" a little higher
oil pressure than Chevys - but not 100 psi +.
My FE in the Shelby has a startup pressure of 100+ when cold but that will go down to abot 80 psi hot above 2500 RPM.
Its been that way for years and at least 10 000 kms - I have had zero problems with the drive gear.
There is a Cleveland spezialist in Neustadt/W - I could send you his phone or email if you wish.