Nice job, these more recent pics show more of the steps. Have you read the article on annealing and orange peel in the LL? Vol 24.1 Issue 90 April 2014 starting page 23.
I’ve not found definitive proof that planchets were annealed at the mint – that would have been a massive operation. What is known is that the mint contracted the making of planchets to an outside contractor. This info is in Kevin’s materials. My impression was that the planchets arrived at the mint ready for striking. I can’t imagine the mint ordering millions of planchets, then sending them through the oven. Surely this would have been done by the company who made the planchets, where they had the room and equipment. But I could be wrong, and there is the possibility that they could have annealed some of the planchets.
A difference of 175 degrees would have been a huge difference in the annealing furnace, and would have altered the steel to a degree noticeable by the human eye. See the photos in the article I mentioned. The conclusion is that the planchets were overheated, but not the dies.
Collecting Flying Eagle and Indian Head pennies never made more cents!