You have to sonic test them. Saying that this vintage 360 was "as thick as the 340's" dont mean nuttin. Some of the Worst block I have ever had the displeasure of dealing with were 340 blocks, core shift was bad back 40+ years ago. The newer blocks are way better. Better castings, better quality control, better machines and less human influence. If I had my choice out of any block laying around would be the Magnum blocks. They may not have as high a Nickle content, but the core shift is minimal and the blocks are more true.
