It's a pity the facades won't be preserved. Demolish the insides completely and replace them with double height, through-block office floors with cantilevered, column free ceilings, extending across both buildings which handily have the same window configuration. Each floor would have a double height row of two windows atop each other.
That might cover the entire commercial allocation, and build something contextual on top, toward the 58th street side, up to around 1200', for the residential portion. This would create a handsome staircase effect between One57 and Steinway.
But no, just
Taer It Dahn! Nothing worth preserving here!