What is valve ping? If you mean the clicking of the lifters then vlve clearance can and should be adjusted as a regular maintenenace item. If you mean emgine ping which is another word for the sound of preignition or knock this is another issue related to the knock sensor and timing. If preigntion is occurring on a reguler basis engine damage can result.

There is no standard mileage before engine rebuild. The indicators to consider would be oil consumption and compression. If it comes down to rebuilding I would swap the engine with a used one of lower mileage. Never heard of anyone rebuilding that engine.