I could have purchased the original L78 short block for my 70 Nova. I traced the car back a couple owners and it was a speed shop that had it.
Since they knew I had the car they put a premium price on it. Problem is they decked the numbers off and I couldn't justify the price tag without the numbers. Plus the top end was gone, Heads, intake, dist. and carb.
Only info I got out of it was the Cast date which was unusually early.
So I'm sure there are other orphan blocks that will never make it to the list due to machining.