This repo should describe how to properly use proj4 with the official Romanian projection.
The verification_points directory holds some shapefiles with points in stereo70 and
their correspondent in WGS84.
The grids/stereo70_etrs89A.gsb file is a standard binary shift grid
for Romania, provided and created by Daniel Urdă
Transform from Stereo70 to ETRS89/WGS84
cs2cs +proj=latlong +datum=WGS84 +to +proj=sterea +lat_0=46 +lon_0=25 +k=0.99975 +x_0=500000 +y_0=500000 +ellps=krass +nadgrids=stereo70_etrs89A.gsb +units=m +no_defs -f %.8f -I /usr/share/proj/coordinates.txt
Transform from ETRS89/WGS84 to Stereo70
cs2cs +proj=latlong +datum=WGS84 +to +proj=sterea +lat_0=46 +lon_0=25 +k=0.99975 +x_0=500000 +y_0=500000 +ellps=krass +nadgrids=./stereo70_etrs89A.gsb +units=m +no_defs -f %.8f coordinates.txt