This is similar to the question on the prior page, which way around do you install the manifold gasket when it has one fiber side and one steel side?

Both surfaces are cast iron and machined flat, so what's the difference? I think the answer is, the steel side goes toward the hotter surface. The cylinder head is water cooled, while the exhaust manifold sometimes gets near red hot with high throttle operation. Since the manifold is likely to see more physical motion due to thermal expansion, I would put the metal side of the gasket against the manifold. Until someone might come up with a better reason, that's my story, and I'm sticking to it.