problematic 2.4" LCD

You have a regular 3.3V module that can be selected for 8080-8 or 8080-16 parallel interface.

You can connect it directly to a Zero, Due, Teensy-3.x with a flex-ribbon adapter.

If you want to use a 5V Uno or Mega2560 you just need 21 level shifters.

Life is simpler (and cheaper) with a ready-made Arduino Shield that already contains level-shifters.

David.