Tom, if you frag a lifter, it will be a very bad day.
If this was my engine, I would pull all the plugs and remove the valve cover on that side. Then place the tip of the stethoscope on the push rods, coming in from the back of the head. While you do that, manually rotate the engine using the crank bolt, a deep socket, ratchet, and long pipe (or your jack handle). If you can consistently hear a difference with that one lifter/rod, as you go through full rotations, and the other cylinders are reasonably consistent among themselves, and don't have the anomaly sound, then you're going to have to remove the lifter.