Offhand two main points of contact occur to me between Buddhism and
"Grace". I'm not sure how theologically correct these are, but they
might be worth looking at.
1) In the Pali Canon and in stories such as in the Dhp-a the act of
putting faith in the Buddha is often enough for someone to get a
heavenly rebirth. This sounds a lot like the Christian idea of faith
being salvific. The difference would be that Christianity sees heaven
as the end of the line, whereas Buddhism sees it as a state from
which a being eventually falls.
I haven't checked the Angulimala Sutta, but IIRC he gains this sort
of faith to begin with. He then, of course, goes on to become an
Arahant.
2) Pure Land Buddhism goes further and allows for faith in Amitabha
to enable one to be reborn in a heavenly realm as a non-returner.
This sounds, on the surface of it, to be very much based on 'other
power' like in Christianity, and to be fully salvific even in
Buddhist terms.
I'm not sure, but perhaps this 'Pure Land' is related to the sorts of
very high heavens which can be attained by advanced meditators in the
Pali tradition. I'd be very interested in hearing if this has been
studied.