I downloaded LiDAR data from Slovenia (link on the bottom). After searching google for the right projection, I found that normally I should use MGI 1901/Slovene National Grid; EPSG:3912 or Slovenia 1996/Slovenian national grid EPSG:3794.
With these EPSG codes, the projection is somewhere in the water. So I went on searching and found the EPSG code 3787. That's something Military Geographic.
These projection is almost correct, but I still have to shift the False Northing about 8 Meters. Yet I have very little difference on the Lidar projection.
In Global Mapper my main projection is set to Mercator and I am using the normal World Imagery as my base map.
The LiDAR files are from this site: Lida GIS Viewer (on the right side, check one of the checkboxes and click in one or more square on the map to download)
What do I have to do, to get the projection correct?