I'm trying to replace worn cam & lifters in a 235 engine from a '55 truck, 3 speed overdrive trans. The old lifters appear to be the original 838774 part with a hole in the pushrod cup and a hole on the side of the lifter. Replacement mechanical lifters I've found (with or without cams) are all missing this hole. Can anyone give guidance on using lifters in this engine without the hole? Thanks!