It *might* be worth close to that much (in terms of increased value to his car) to the person who owns '69 Z28 (VIN 124379N680067) which doesn't have it's original motor - assuming this one IS the correct motor...
... but to anyone else? NO WAY... I wouldn't give $800 for it.
PS. I'd guess that the original cars that the great majority of these 'orphan' engines came in... are mostly crushed down to scrap metal by now.
Hey Gary, Antique comment I know, but... I'm sure you're right for a majority of orphans, but ours is just one example of a 69 Z28 without it's original block. There are a ton still out there and I'd say there's a pretty good chance that there are quite a few original blocks just waiting to match up.
I'm still looking for our Z28 block, 597037. I'd love to have it obviously, but if I found it for $8k he could keep looking for another sucker...