The earliest I have personally seen was October 1962. I tried to buy the engine from the guy but at the time he wasn't interested in selling.....maybe if I tried him again. Here was the story:
Joe from Denbeste Motorsports called me and said they had a customer in Denver that had bought an AC Cobra from them and needed help sorting out an issue, couldn't get it to start. They sent me a whole box of parts of anything they could think of that was causing the issue, distributor, plug wires, spark plugs, coil, etc. I went down there and looked at it, diagnosed that the coil was bad, replaced it, easy.
This guy and I start talking and he said yeah my dad had a 63 Galaxie wagon 427. He ordered it with the 406, but they didn't live all that far from the Ford factory, and somehow the factory called the dealer and told them they would like to drop a newer engine offering, the 427, in this car as long as the customer was fine with them putting some miles on it and testing it. He was reminiscing and said yeahhhh I wish that car was still around but the car rusted out, at least we still have the engine. I asked him where the engine was, and he opened up the door on his front work bench and all the pieces were tucked up under there. Block, heads, intake, etc. I looked at the casting dates and they coincided with his story almost exactly. I offered to buy it all from him but you could tell it was a bit of a keepsake for him.