This type of leak is common regardless of the brand of car.

You will need to clean both surfaces but don't try to "file" the down. The goal is to clean out the pits, fill them with epoxy ( like JB weld ) and sand lightly to bring the epoxy to the same level as the metal.

When installing the gasket, it is a good idea to _lightly_ coat the area around the coolant passage with silicone sealer.

I can't emphasize this portion of his advice enough! The key word is "lightly"

Clean the threads with a tap. Go gently. Those are alloy heads and it is easy to mess the threads up. If the bolts look "iffy", replace them. Use a torque wrench when you re-install the manifold.

Use Never-seez or its ilk when you re-assemble.

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now