I've got an LCD module with a 26-pin connector for a Pi 1B, and a Pi Zero W with a 40-pin header. Can I use the LCD with the Pi, and if so, how should I align the connector on the header?
It should work as the first 26 pins remained largely the same (as can be seen in the image below). As for orientation pin one will be the pin closest to the SD card and is where you should attach the LCD.
Note: depending on the header used on the LCD you may have difficulty fitting the board. If this is a problem stacking headers, jumper wires or a Pi plate are a cheap fix.