I started with a 427 Center oiler and two flat cams later, I said to heck with it and bought a Pond Aluminum 482 short block from Keith. Much better off than getting an original. With that said, machine work still needs to be done to these blocks to correct certain manufacturing flaws and you want to go with someone who has experience with these motors like Keith Craft or Mike at Mitech.
http://mitechengines.com/index.htm And of course Barry of Survivalmotorsports.com who already responded to your question. In fact you can also include George of
www.gessford.com (or 402-463-9844)