The HOMO/HOMO-1 ratio of the partial photoionization cross-sections in C-60 is computed to high accuracy employing a convergent one-centre expansion and a local density approximation (LDA) hamiltonian over an extended energy range. Excellent agreement is obtained with available experimental data in the low energy range. The high energy behaviour shows no sign of predicted amplitude modulation or of high energy damping. A modulation in the oscillating frequency is instead clearly revealed, consistent with the few available high energy data, which suggest however a more regular increase with increasing energy.