I think you mean RG 142 which is 50 ohm. RG58 is a lower quality coax but at VOR freqs not much difference in loss. However that is not the only consideration. The lower quality means less dense shielding which can result in noise getting into the signal.
There are lots of variations in RG58 quality also.
RG 142 also meets current flammability standards, RG 58 does not.
That said, RG58 has been used for VOR antennas for years.
Dan