How to remove old gaskets and carbon?

For the gasket just use a razor blade, careful not to gouge the surface too much, as for the carbon use some carb cleaner.

3m makes three different "pads" that go on a variable speed drill, each color is for a different type of metal, IE: aluminum, steel etc. make sure you use the right one, as listed on the package, using the one for steel on aluminium is a bad thing as it will score the metal. If it isn't aluminium, then you can also just use a soft wire wheel that goes into the same variable speed drills, it removes pieces of gasket and carbon like crazy. If you need to remove a stuck gasket that has metal in it, use a gasket scraper, just be careful not to gauge the metal surface.

Use a gasket scraper, its like a heavy duty razor blade and that makes it less likely to mar the gasket surface. You can then use a flat file to gently smooth the mating surface.

Use a strong scraper with a good blade, and then clean it up with steel wool or some fine emery paper - but be careful. If you score the metal with the scraper or rub too much away with the paper, it will leak - especially common if it's an alloy head or block.

Good luck!

I would pay the pros to do this. You can really mess things up if you don't do it right. A good machine shop will clean and resurface the heads and use a chemical or heat treatment to remove all carbon. It's well worth it.