between these being average production line castings, and who knows how much core shift when they were banging these things out, i wouldn't be surprised to find an 1/8" of variation in that area. how high are you wanting to twist this thing?
Not particularly high and not a ton of power. Maybe a bit over 1 HP per ci. But I don't want to get things so thin with grinding that a crack develops and coolant leaks into the crankcase.
