I would say 300 tops. But location is key..

 

Gotta ask ,where do you get these 'one of a kind' blocks from?
Believe this is the second 'one of a kind' you've posted about.

 

"south west ontario canada"

Lives just across the river from the Tonowanda engine plant where they were built. This could get interesting. I would also like to here the history.

 

i dont have this in my hands yet,but i have had alot of strange stuff in the last couple years. no stamp are not that strange when you run thru 20 0r 30 a year . the 512 block with 4.09 bore was the oddest i have ever had

 

I have that exact block, standard bore, never been sleaved; I paid $ 150 for it about 5 years ago, and had it bored .30 over, and everything new

 

$300-$400 What is casting date on block ??? May be interested in it and Im just across the river from U.................

 

Look and see if it has a stamp on the bottom, on the machined part of the starter mounting pad or on the oil pan rail near the starter mounting pad. If so, it was a service replacement block. They did not do CE stampings in 67 and earlier. They stamped it down on the bottom. Would be T### format (Tmmy)

 

X2, I have a 66 L78 block with original blank pad. The assembly date, T0706 is stamped on starter pad.