He didn't. He found it for $2500 + a core block. I think in other message boards he somehow was related to Ford or had a Ford hookup so this was probably straight from Ford back when they still serviced these engines directly. He probably got it back in 2019 or 2020.
Mix in pandemic supply chain issues and inflation and add in the important step of Ford not producing these motors on an assembly line anymore and you go from $2500 + a core block to $5-6000.
EDIT: the above are just wild guesses on my part and hopefully
@PhoenixM3 is still on the forum and can reply. he did say he had to fly somewhere to get it crated and drive it back to his place so he might not even know how that core block for new engine program worked. Sounds like he bought it off someone else who did that swap.