In your area there were a lot of big block engines bought new in a crate from the local car dealerships to drive irrigation pumps back in the mid to late '60's. I don't know about 428's, but I was in a Tulia, TX Chevy dealership in 1965 and there was a 409 crate engine sitting there waiting to be loaded. I was drooling over it, and one of the locals laughed and said, "Boy, it's just a dadgummed irrigation engine. Nuthin' to get excited about." As I looked more it was a truck engine with a little 2-barrel carb on top. Later we were out at an uncle's field, and he had a SBC driving his pump, running hard on a governor at about 3500rpm working hard to pull the water from nearly 200' down, and he said he was trying to get by without buying a big block as long as he could, using junk yard small blocks.
You might pull it apart, marking all of the parts for location, and take the block to a good machine shop to have it cleaned up and checked, with an estimate of what it'll cost to get a short block (or complete engine) put together the way you want it. Then you can compare costs to the crates available.