many thanks for your reply.
I think it's very unusual, that Australian/Newzealanders are collecting race record of 'German Thoroughbreds' several decades ago. On the other hand understandable after so many wins of Germanbred race horses all over the world.
You have already found the websites, who are reporting about German Racing.
Only Newspapers in Cities and Towns, who have Horse racing tracks reporting about this Sport, but the don't provide the info you are looking for.
Here In Germany we have the "Sportwelt" (our racing paper, 2 - 3 issues every week), publishing since 127 Years and "Vollblut" our Thoroughbredbreeders Magazine. Sorry to say, there isn't an Internet Version available.
I have a collected over years a library of books , magazines and sales catalogues. I can check some data, you are looking for. Another Option is to went through the Annual Racing calenders.
At least I can tell you the "racing career" of Windwurf (Kaiseradler-Wiesenweihe by Birkhahn), from 1974-1977, foaled in 1972, bred by the "Ravensberg Stud", Trainer: H. Gummelt:
27 starts-11 wins, 5 second place, 2 third place, 1 fourth place
earnings 1.315.640 DM
The complete list I will try to send during the Weekend.
Hope I could help