  The redshifts of faint radio galaxies identified with giant radio source
candidates selected from the sample of Machalski et al. (2001) have been
measured. Given the redshift, the projected linear size and radio luminosity
are then determined. The above, supplemented with the axial ratio of the
sources (evaluated from the radio maps) allows to constrain their jet power and
the dynamical age using the analytical model of Kaiser et al. (1997) but
modified by allowing the axial ratio of the source's cocoon to evolve in time.
