The FFC and the DA1 and DA4 maps use exactly the same outline.
FFC says it is 10 miles/hex, DA1 says 24 miles/hex and DA4 (as well as DA3, showing the area to the south) say 12 miles/hex.
All the text labels from FFC are on DA1, as well as quite a few others. DA4 only adds a couple of extra labels to DA1 plus about a dozen forts with roads connecting them to towns.
If you click on the link in my signature and go to the Blackmoor folder, you'll see copies of all of them, as well as a combined DA3+DA4 map. These maps are also on the map page of the Blackmoor Archive, which you can access using the link at the top of the page here.
My suggestion would be to use either 10 or 12 miles/hex - if you're used to 24 mile Mystara maps go with 12, if you use the 5 mile Wilderlands maps go with 10.
I also did a 4xsize BM map which you can use at 5 miles/hex if you need it, that's on the flickr page as well.
For content I'd use DA1 or DA4, as it uses exactly the same map as FFC, just with more labels.
As for the ZG map - that's a completely different animal.
There are matches between the ZG and DA maps, but there are also a lot of changes. If you are planning on a campaign, you need to decide right at the start which map to go with or it will cause problems.
I'm afraid I haven't done a replica ZG map yet, but Havard has produced a map which tries to combine the ZG and DA maps, which should be on the maps page of the Blackmoor archives.
I hope that helps!