Agree with Michele Felice.
Disklavier or not is a non-issue in the C7.
New action or not is a non-issue with the Steinway M.
1936 or brand new is also a non-issue for the Steinway M in this comparison.
A Steinway B is what I'd usually compare to a C7, assuming the pianos are in good condition.

Since you're considering it for a solo recital, how big is the hall?
(The length, the width, the height of the ceiling, and seating capacity.)
Usually, big hall --> big piano. Even in a small hall, I think I'd still prefer a bigger piano but play with the lid lowered.
