  The dependence of breakup cross sections of 8B at 65 MeV/nucleon on the
target mass number A_T is investigated by means of the continuum-discretized
coupled-channels method (CDCC) with more reliable distorting potentials than
those in the preceding study. The A_T^(1/3) scaling law of the nuclear breakup
cross section is found to be satisfied only in the middle A_T region of 40 <
A_T < 150. The interference between nuclear and Coulomb breakup amplitudes
vanishes in very forward angle scattering, independently of the target nucleus.
The truncation of the relative energy between the p and 7Be fragments slightly
reduces the contribution of nuclear breakup at very forward angles, while the
angular region in which the first-order perturbation theory works well does not
change essentially.
