Well I guess you do know, got proof Al?
The proof is in historical accounts from people were who were there. I got my proof from Chapter 24 of Craig Shirley's book, Rendezvous with Destiny. The chapter is titled "Motown Madness" and recounts the negotiations between Reagan and Gerald Ford which broke down.
It was understood by everybody including Reagan that Bush was the second choice. Time had run out to make a decision and Reagan went around the room and asked if anybody disagreed on Bush and hearing none he said "Well, let's get him on the phone" (pg. 364).
The footnote on the final choice was Richard Allen's article in the New York Times "The Accidental Vice President". Among other things Allen inferred in the article that the search for a VP had been an unstructured one. Dick Wirthlin, Reagan's pollster, wrote a follow-up letter to the NYT disagreeing with that saying that the search had always centered on 3 names...Ford, Bush and Howard Baker.
Both Allen and Dick Wirthlin were in the room when the decision was made, along with Ed Meese, Bill Casey and Peter Hannaford.