It shouldn't be very difficult. I always label which wire went to which terminal of the motor. They sell these at in the electrical section of hardware stores. They are just little numbers that stick on the wires and you can place them on the old motor where the wire was to use as a refrence. Another option would be to use tape and write on it. This proper labeling will prevent you from making the air blow in instead of out. As far as the mechanical side I am not familiar with the set up of the 1962 Chevy. It sounds like a fun project.

Chevy 1956 3200

"So she said, "either I go or the truck goes!"....Hmm, I wonder what she's doing these days?"