Not mine and I know absolutely nothing about it - Ran across this on the London UK Craigslist (it has a picture of the block and sleeves):
Up for sale on a rough casting 427 Yenko block that has the exact numbers as a ZL-1 block. We bought it with intensions to finish it and sell it for 15,000 but we need to make room and it's got to go. It comes with the cylinder inserts (8) and a used set of early 4 bolt main caps. A great way to own a part of Chevy history.
http://london.craigslist.co.uk/pts/2478157971.html
I really hate to post things like this - but if this one isn't some sort of a scam than it might be worthwhile for someone on this site to follow up on it. Please feel free to delete this post if inappropriate.