The actual distance between the torque converter and flex plate is not of concern because it should be shimmed. What is important is how much the torque converter comes out of the pump, and that should be about 1/8". In one of the linked videos the guy says 1/8 to 3/16", in the other video the guy says 1/16 to 1/8".
https://www.youtube.com/watch?v=afzBif5snOg
https://www.youtube.com/watch?v=efjVRicuFrA
As can be seen in this 2nd video, an incorrectly set torque converter can eat up a pump in a short amount of time.