I too used to be under the impression that all later blocks were super thin wall that couldnt be bored over. I had this crazy block once... the numbers on the sides of it looked like the had been ground off or something. I cant remember everything that was on the front drivers side of the block but I do remember it had 318 there. It had a bore of 4.07 which if I remember right is .030 over 340 pistons. I used the engine for a few months before I sold it. Wish I had hung onto it to figure out what the deal was.