Matthew Breit told me that he is going to release his maps (I assume his non-release-version Quake 3 maps) in the .map file format under the GPL, as well as the textures. Here you can read the dialogue so far.
Now I know that your engine is based on the first version of Quake, but perhaps his maps can still be of use for you.
Tell me what you think and if you want to adopt/remix the maps to Nexuiz' needs as soon as they are released.