LA blocks
The thing is, the MOST important issue is the thinnest area in any given bore. Doesn't matter how thick 7 cylinders are if one is thin. The old blocks are over 50 years old, and corrosion inside the water jackets takes its toll. And the old claim about "much thicker" cylinders is greatly exaggerated. Even if they used "340" water jackets, that would only be .040 difference, or .020 per side. Big deal.