Look at the u8g2 library and the use of a page buffer instead of a full buffer for the display. Depending on what you want to display, the u8g2 library includes the u8x8 library that needs no display buffer, but is limited to fixed-pitch fonts and no graphics.
The 128x64 display full buffer needs 1024 bytes of ram, and the SD library uses a 512 byte buffer, leaving 512 bytes for everything else.
Also look at sprintf_P, that will store the format string in program memory, saving some ram.