It is well-documented that Reagan waited until the very last minute at the convention before making his decision. He had not wanted Bush and was very hesitant to choose him but in the end, he chose pragmatism. He knew the establishment hated him, he knew the way to victory was to unite the GOP and unfortunately, that meant making a gesture towards its establishment players.
I am going to read up more about this. I also got a post last night from someone who also posted to me the details of the ties and friendship between the Bush family and the Hinkleys. I guess a reporter called it "the most incredible coincidence in Presidential assassination attempt history."
Interesting.