Back on the car and runs fine. I have to put a strobe on it to check the advance. Feel free to add tips.
When I rebuilt mine, I purchased all the needed parts from the Distributor Doctor in the UK. The drive dog removes easily by driving out the straight pin. There’s a thin fiber washer that goes between the drive dog and distributor body which often is missing. When you spin the distributor plate in the video it sounds a bit loose. You may need to replace the bronze bushing in the lower distributor body.
Also, there are several wicks that should be present. The bottom of the distributor body is a well that holds about an ounce of oil. The wicks keep the upper parts lubricated. You’ll see a hole mark “oil” and that’s where you periodically add a few drops of oil to replenish the well. Finally, make sure the spinning plate is stamped “14”. This is the correct plate for an XK120 or 140. Sometimes the spinning plate has been changed with a higher number plate, which will allow too much mechanical advance.