This is an uncommon problem. And I must congratulate you, Mike, for having exhibited uncommon patience and tenacity in dealing with this.
There are few problems that can withstand the judicious application of time and money.
Assuming 1. that you were sold the right parts and 2. that the front cover was in good enough shape to allow for the oil pump gear chamber and new parts to measure within spec, and 3. that the pickup tube and strainer have no holes or blockages, the only thing left I can think of is that you have something that is blocking the flow of oil either before or after the pump, not letting any oil flow to prime it. You should be able to check the passages by removing the front cover (again!) and the adapter and blowing compressed air through all the passages to make sure they are clear. The passages after the filter (the oil gallery in the engine), I believe, originate at the center pipe that the oil filter spins onto. If I am correct about that, a blockage in the engine could be detected by trying to blow air through the threaded oil filter center pipe, before you remove the adapter plate.
If I read your post correctly, I am most concerned about the running to temperature without the oil pump functioning. That could have been the end of your engine bearings. But hey, they run engines on the Duralube commercial with no oil in the pan for a while without the bearings melting, so maybe you will be lucky.