Thoroughly clean the gasket surfaces on both the cylinder heads and the engine block, ensuring the threads of the attaching bolts and the threaded holes in the engine block are free of dirt by running a tap through them. Determine the type of head gasket being used; steel head gaskets require a thin, even coat of sealer on both sides, while composition steel/asbestos gaskets should not use any sealer. Position the gasket over the engine block dowel pins with the bead side up, then carefully lower the cylinder head onto the engine without disturbing the gasket. Coat the threads of the cylinder head attaching bolts with a sealing compound and install them finger-tight without tightening at this stage. Gradually tighten each bolt in a sequence until the proper torque reading is achieved, checking to ensure none are missed. Install the exhaust manifolds and each valve lifter into its proper bore, using 'Molykote' or an equivalent as a coating. Apply a small amount of 'Molykote' to each end of the pushrods before installing them in their original positions, ensuring they are seated properly in the lifter cavity. Place the rocker arms and corresponding rocker balls onto their original studs, lubricating the rocker balls and valve stem ends. Adjust the valves and install the rocker arm covers, using a gasket for early models or RTV sealant for newer models. If a gasket was previously used, replace it with a new one, tightening the bolts to specifications; if no gasket was used, apply a 1/2-inch bead of RTV sealer around the sealing surface and install the cover while the sealer is still wet, torquing the bolts to specifications. Install the intake manifold with new gaskets and the remaining engine components, fill the radiator with coolant, start the engine to check for leaks, and adjust the ignition timing and valves as necessary, rechecking the coolant level once the engine reaches operating temperature.