Jim,
From everything I've read the Mexico block is the preferred block. The mains are supposed to be heavier and the cylinder walls are thicker, I also read on the HAMB that the block has more nickel in it which is said to make it more durable. The engine I'm building is a 1980 block.
Thanks for your reply .... sounds good to me .
(at this time ... I'm just keeping it for a spare , has a "rebuilt tag" on the side of block . like that means anything).
thanks again, Jim