Never, ever disturb the running relationship between a cam lobe and the lifter it's gotten used to running with. Any wear on the lifter will have corresponding damage to the cam lobe whether or not it's visible to the naked eye, so installing a new lifter on a used lobe will only exacerbate the wear that's already there. Button it back up, adjust the lifters per the service manual, and swap out the whole works, cam, lifters, and timing gears when you rebuild the engine.
Jerry
