According to the book " The Standard Directory of Proof Marks", it seems that the current proof laws in force in Germany are basicly the same as their 1939 Proof Laws. Some language and proofing methods were changed in 1968 but mostly that pertained to guns made in Germany for export to other countries. As far as I can tell from a quick re-reading, the proof pressures have not changed. All the guns you mentioned should have been proofed to the same levels no matter when they were made, after 1939.
This is a very good book to own, especially if you are going to try and convert a shotgun to a rifle. You should buy one and study it carefully, it will explain how the guns were tested and to what levels of pressure. Maybe more importantly, it shows you many of the proof marks that were used by many different countries and gives you the proof levels for each mark.
I think all gun builders and collectors could benefit by owning one of these books and studying it closely. I hope this helps you out. Bob H.