Seems to have worked 
Current radio firmware listed as “05.05.58.00_GENEU-4G_005.026_000”, which matches the filename (MC7304_GENEU-4G_55580.iso), though the date is quite old in this other version string: “SWI9X15C_05.05.58.00 r27038 carmd-fwbuild1 2015/03/04 21:30:23” Maybe there was no radio firmware update needed. In any case, someone should update the firmware download page to make things a little clearer…