Same as mkennedy, I suggest to georeference against a map of today, like OpenStreetMap or Google satellite. Road junctions, railway crossings and river bridges have not moved over the time. On the other hand, surveying has improved a lot. Keep in mind that they had no satellite imagery, and many things were just collected by sight.
The reference meridian of ferro never had a fixed point like Greenwich, and the location was adjusted over the centuries while geodesy improved.
I have georeferenced your map once against the coordinates in EPSG:4805 MGI(Ferro), and once against recognizable points from OpenStreetMap (EPSG:3857). They offset near the town of Sisek about 400m:
You can play with the +towgs84 values to get them together:
+proj=longlat +ellps=bessel +towgs84=0,0,-100,0,0,0,0 +pm=ferro +no_defs
but this does not fit across the map. The prime meridian of ferro is hardcoded 17°40'W. You could use the value given above, but need a different +towgs84 parameter set. Alignment does not improve though.
Reading through http://rcin.org.pl/Content/40957/WA51_58447_r2013-t86-no4_G-Polonica-Affek.pdf I think that your map is part of the third austrian military survey, which was not based on the Bohnenberger ellipsoid (as the second survey), but already on Bessel 1841. This leads more towards EPSG:4805 as GCS. The map projection is described as polyhedric.
This source could provide some details of the same map type: http://mapire.eu/static/pub/cadastral_timar_biszak.pdf
This page also gives some details converting towards WGS84: http://spatial-analyst.net/wiki/index.php?title=MGI_/_Balkans_coordinate_systems