A3 is still permissible for breeding under the German system. I would get the results from OFA before making a final decision. I have no problem with seeing NZ in a pedigree, so long as there is not a lot of them. Fast normal is just fine, and I have known two fast normal dogs to throw normal pups. People like to equate fast normal with OFA fair, but my guess is that some fast normals would range in normal, and some would range in fair. It is not a direct correlation between the two, and no way to really tell, by the the score where they would fall in the OFA system.
Another thing to look at in the German system is their overall HD score which takes into consideration their progeny too. So what they produce.