Carefully lift the manifold from the heads and set it aside. If the gaskets are stubborn, you will need a scraper to remove the dregs. Since we're going to replace the cylinder heads, there's no need to make sure that none of the gasket material disappears into the intake ports. Unbolt the headers or exhaust manifolds from either side of the engine. In most cases, they will likely be suspended by the exhaust system. Just make sure they don't compromise working room when you replace the heads. Unbolt the rocker arms and pull the pushrods out. Remove the cylinder heads. Stuff the cylinder bores with rags to keep out potential crap and make sure that the block deck surface is free from debris. Inspect the water and steam holes to make sure they are open and free to flow. Use a gasket scraper to peel intake manifold sealant residue from the block rails and apply solvent or something similar to clean the surfaces.