This is already easily achievable.
Turn off AA/AF filters in the video options.
Set resolution to 640x480 (original).
Play the game in windowed mode or turn off upscaling in nvidia control panel (under "Adjust desktop size and position" select Scaling mode to "No Scaling" - if your monitor doesn't support it, also set "Perform scaling on" to "GPU" and check the override).
Edit: And seeing as any modern monitor has way higher resolution than that, if you want the window to be larger, but still without any distortion, once again go to the game's options menu, select scaling method to "integer" and choose a resolution that is a multiple of 640x480.
Post edited February 25, 2020 by Jann180