I saw this thread and got to thinking about some big blocks I had around the shop. One is a 4 bolt 512 H-31-70. 8th mo. 1970 It is an old race car engine. Std bore and needs one sleeve. It has been decked so there is no number code. I think that makes it pretty clear, by the date code, it would have to be a 454, not 427 or a replacement block bought across the parts counter for racing or replacement. If it came in a car could it have been a real late 70 or a real early 71? I guess that depends on when the 1970 line closed for change over to 71..
Adger Smith
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