I am about to take my block in for preparation so I need to make a decision on whether to stay with the 92mm bore or bore the engine for the 560 96.5 pistons. The cost will be about the same-if I use the turned down 92.5 pistons I will need the engine rebalanced which will cost about the same as the extra machine work for boring to 96.5. If I use the 560 pistons I have the entire original 560 rotating assy so I should not need rebalancing. The flywheel is statically balanced and not balanced as an assembly like an externally balanced engine. My main concerns are the head gasket and piston rings if I go with the 96.5 bore. I found a company that will modify the 450 head gaskets with larger dia fire rings for the bigger bore so I feel comfortable with that.
I don’t feel there is an issue with the coating on the 560 pistons-it has very little ferrous content and a very strong magnet will barely stick to it. As long as it is not steel there should not be any compatibility issues with the iron cylinders. What I am struggling with is which piston rings to use with the 560 pistons. The original rings are steel or ductile iron which is incompatible with an iron cylinder. Deves has cast iron rings for this application but I keep hearing about rapid cylinder wear, etc. Is this just BS?

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Tony H
W111 280SE 3.5 Coupe
Manual transmission

Past cars:
Porsche 914 2.0
'64 Jaguar XKE Roadster
'57 Oval Window VW
'71 Toyota Hilux Pickup Truck-Dad bought new
'73 Toyota Celica GT