[Torch]

Pull the valve covers off and watch the valves open and close, even better yet get a ruler next to the rocker arm and measure how far the valve is being pushed up, when you find the one that is bad undo the rocker and pull the push rod and a verify that it isn't bent.

If the push rod looks fine you will not (or should not) have to pull the head off but you will need to pull the intake manifold off. On most V-8 engines it is impossible to replace the lifters without pulling the intake manifold off.

An '84 is going to be loads of fun, there are wires and hoses everywhere but once you get down to the manifold it is just like any other V-8 manifold. Make sure you have new gaskets and sealer before you pull it off though.