Just looks like a big Boat Anchor to me!
It looks like a 427 Side Oiler, maybe a service block? Where did you find that old bird? Are you going to use it? I've got the top end parts to make a nice motor but no block. Like others have said, check the bore dia. It doesn't look to have been used and I've seen a lot of NOS 427 blocks that look like yours. The first time you rebuild one all those paint markings come off. It looks to be in good shape. They've actually come down in prices lately with the availability of the new Genesis blocks. Hopes this helps some. Share the story with us, it's gotta be good.
