Thanks for the input so far - keep it going.
In all fairness, I should add a couple of concerns that the owner has about this block - 1) It's .060 over. No ridge in the bores, but some surface rusting (not pitted, but probably should be derusted, then honed). Pretty sure it will clean up without a problem. It was like this when I got it, been covered/garaged since I had it, but since I thought it was a standard bore for years, I was going to bore it .030 and use the L2242 pistons I had bought for it to assemble. He's afraid he'll have to sleeve all of the cylinders, or it won't be usable (like my 500 lb. boat anchor/Protect-O-Plate). 2) Initial disbelief that it is his legitimate block. My answer back - "why would I restamp a block with a random number, or any number different from my VIN ?". No answer from that question, but his interest remains.
If this deal was reversed, I have the opposite opinion - usable or not, it is the original block - that only happens once, long ago. There sure are a bunch of non-matching-numbered cars out there.
BTW - my engine is stamped as you see it (pic), his is 12/15. About a month difference in build dates (1st week December to possible 1st-2nd week in January).