Dear Metallo,

Hope you're well and stay so. It is a good idea to take the head to an automotive machine shop, so they can check it for: (a) any warping; (b) to make sure there are no cracks, not all of which may be obvious; (c) to ensure there's no corrosion, that makes impossible a good seal between the head and the gasket. Presuming the head passes inspection, they can also replace valve guides, etc., and clean the head's surface.

If the head-gasket comes away cleanly from the block, the cast iron can be cleaned with fine steel wool, the cylinders first having been "stuffed" with clean cotton cloth, to keep out dust. I'd then wipe the surface with methyl ethyl ketone (MEK) - a highly-flammable solvent - to remove any trace of dust, dirt, or other contaminants.

If you can't find MEK, acetone is second-best when it comes to getting metal (or glass) surgically clean. Be sure to wear nitrile gloves when using MEK: it is a known carcinogen.

Hope this helps.

Yours faithfully,

Spook