X2 on the wall thickness of the cylinders.
It may be worth to cut open a old block to see how much meat is actually there.

All piston rings for aluminum blocks are chromed.

All oil rings for cast iron V8 blocks are also chromed.
All upper compression rings for US 450s are chromed.
Upper rings on 450s for other markets are molybdenum coated.
The second compression ring on all 450s is molybdenum coated.

Does this mean that one should be able to run a set of chromed 560 rings in a cast iron cylinder?

__________________

76 240 D. Bought in 1998 for $25.
85 300D. Got it for free with a bad engine. ( Sold )
60 Unimog 404. What was left of it, was given to me. Now powerd by 617A.
88 560 SEL. Bought without engine and trans. Now powerd by 617A.
67 250 SE. Cuope. For resto or sale.
64 220SE. For resto.