  We present results of our continuing study on mixed-action hadron spectra and
decay constants using overlap valence quarks on MILC's 2+1+1 flavor HISQ gauge
configurations. This study is carried out on three lattice spacings, with charm
and strange masses tuned to their physical values, and with m_l/m_s = 1/5. We
present results of an ongoing determination of the mixed-action parameter
Delta_{mix}, which enters into chiral formulae for the masses and decay
constants.
