Remember, if it was in that kind of condition, it wouldn't be apart. Just because they say it is a standard bore block, doesn't mean it is. Unless you have some calipers to measure the parts and know what standard specs are, how can you tell? How about cracks in the block, web area, etc... Would be nice to mag check it.
So lets see. Hmm It is a 1966 440 block That he took out of his Dart?! (Nice fit) a few years ago, and now it is apart, but it is a standard bore block? What else comes with this package? Manifolds,oil pan, valley pan, distributor Pulleys and brackets, valve covers? It all adds up. Buyer beware.. Don't look for a lot of us to say go for it. I surely wouldn't. Patience is a lot more economical in the long run. Wouldn't you feel better buying an engine that is complete and running before you spend your money ? The only blocks that are really scarce would be standard 340 or 426 Hemi blocks. Everything else was manufactured in the millions !~ Do some more shopping, or take Dartguy340 s advice, buy a crate motor or shop around for an engine builder who can build one supplying all the parts so you can be sure he is responsible if parts are bad.