Not sure- there have been quite a few people who started casting up aluminum blocks, then for one reason or another, never finished. This is a completely unmachined block and I estimate it would take a real machine shop several weeks (at $75 an hour) to finish macining it, the worst being boring the 16 tappet holes exactly right. FYI, in the late '60s, a whole pallet-load of unmachined alloy blocks once disappeared from Mickey Thompson's So-Cal foundery, and he spent years tracing them but never found them all. A couple of guys went to jail. Don't remember all the details now- I asked Mickey about them once and nearly got my telephone-ear ripped off....