500 vs 512 from 400ci

ValiantS said
You SHOULD be able to get a .9mm in SS for first. Second .9 napier in 4.375"ish bore then a 3mm oil Mahle

That would be about as good as it gets. What about a 2mm oil ring?? The 3mm is only about .120 thou but the 2mm is only about .080 thou. I’m all for the thinnest rings that will get the oil off the cylinder wall.