The present invention provides an internal combustion engine component, such as a cylinder head or tappet block, which is adaptable to a variety of pushrod positions and angles. A large pushrod aperture is formed in the engine component. The aperture is large enough to accommodate one or more pushrods passing therethrough at a variety of different angles and positions. A composite pushrod hole adapter plate is attached to the engine component over the aperture. The adapter plate has one or more pushrod holes machined therethrough at desired angles and positions. A counter bore is preferably formed around each pushrod hole to provide a seat for the end of a pushrod housing. A plurality of different adapter plates, having pushrod holes and counter bores formed therein at different angles and positions, may alternatively be attached to the engine component, thereby adapting the engine component for use in combination with various different engine designs. The component may be provided along with one or more adapter plates as a kit which may be assembled onto an internal combustion engine such that a pushrod passes coaxially through each pushrod hole in the adapter plate and an end of a pushrod housing is positioned in the counter bore around the pushrod hole to form a seal between the adapter plate and the pushrod housing.