  We discuss a Lattice QCD mixed action investigation employing Wilson
maximally twisted mass sea and overlap valence fermions. Using four values of
the lattice spacing, we demonstrate that the overlap Dirac operator assumes a
point-like locality in the continuum limit. We also show that by adopting
suitable matching conditions for the sea and valence theories a consistent
continuum limit for the pion decay constant and light baryon masses can be
obtained. Finally, we confront results for sea-valence mixed meson masses and
the valence scalar correlator with corresponding expressions of chiral
perturbation theory. This allows us to extract low energy constants of mixed
action chiral perturbation which characterize the strength of unitarity
violations in our mixed action setup.
