I am going to chime in because i can: hahahaha
Now, my father was part owner of an engine machine shop / auto parts business for 20-yrs.
His next 20-yrs were spent as a GM parts manager. He told me manufacturers Ford and GM were good for slipping in engines that weren't as badged. So, extra 427's ? slip them into something and badge it as a 402 ? hahaha.
No kidding, some may agree and some may disagree, but excess engines moved on down the line.
As a for-instance, the engine out of my '78 Ford E-250 Van was shown to be a 460 of course. But upon disassembly, my machinist discovered i have a 429 (385 series).
Most medium duty truck engines F500's and F600's etc, do have a forged steel crank and stronger tall blocks and heavy pistons for severe service survival. These engines are normally governed, and are not a high horsepower hot rod engine, but they can be worked Hard all-day without breakage or complaint like for towing a heavy trailer 10-hours a day, and 6-days a week for 300k miles.
I have a '95 GM 366 truck long block I purchased for the crankshaft and building a long-stroke towing engine.
I will scrap the 3-ring long pistons for something a bit different.

I wonder if that may be a marine engine ?
Now i must go look at the casting number on my '78 429. my guess: it will be a D3VE block. maybe not.

 

How much do you want for it and where are you located
here's one of my hd 429 cranks I just had polished during my last build this spring after snapping my 502ci crank in half